% Bugs (sigh) in Computers \& Typesetting --- the most recent errata \tracingpages=1 \input manmac \def\.#1{\hbox{\tt#1}} \font\sltt=cmsltt10 \font\niness=cmss9 \font\ninessi=cmssi9 \proofmodefalse \raggedbottom \output{\hsize=29pc \onepageout{\unvbox255\kern-\dimen@ \vfil}} \def\today{\number\day\ \ifcase\month\or Jan\or Feb\or Mar\or Apr\or May\or Jun\or Jul\or Aug\or Sep\or Oct\or Nov\or Dec\fi \ \number\year} \def\cutpar{{\parfillskip=0pt\endgraf}} \def\rhead{Bugs in {\tensl Computers \& Typesetting as of \today}} \def\bugonpage#1(#2) \par{\bigbreak\tenpoint \hrule width\hsize \line{\lower3.5pt\vbox to13pt{}Page #1\hfil(#2)}\hrule width\hsize \nobreak\medskip} \def\buginvol#1(#2) \par{\bigbreak\penalty-1000\tenpoint \hrule width\hsize \line{\lower3.5pt\vbox to13pt{}Volume #1\hfil(#2)}\hrule width\hsize \nobreak\medskip} \def\slMF{{\manual 89:;}\-{\manual <=>:}} % slant the logo \def\0{\raise.7ex\hbox{$\scriptstyle\#$}} \newcount\nn \newdimen\nsize \newdimen\msize \newdimen\ninept \ninept=9pt \newbox\eqbox \setbox\eqbox=\hbox{\kern2pt\eightrm=\kern2pt} \tenpoint \noindent This is a list of all substantial corrections made to {\sl Computers \& Typesetting\/} since the beginning of 2014. (More precisely, it lists errors corrected since the 19th printing of Volume~A, the 9th printing of Volume~B, the 8th printing of Volume~C, the 6th printing of Volume~D, and the 7th printing of Volume~E. % 2012 for A-D, 2013 for E But it omits changes that are ``purely cosmetic.'') Corrections made to the softcover version of {\sl The \TeX book\/}, beginning with its 32nd printing, are the same as corrections to Volume~A\null. Corrections to the softcover version of {\sl The \slMF\kern1ptbook}, beginning with its 11th printing, are the same as corrections to Volume~C\null. Changes to the mini-indexes and master indexes of Volumes B, D, and~E are not shown here unless they are not obviously derivable from what has been shown. Some (or all) of these errors have been corrected in the most recent printings. \looseness=-1 % volume A \bugonpage A34, line 3 from the bottom (01/09/20) \ninepoint\noindent not, you can say `\.{I\char`\\errorcontextlines=100} \.{\char`\\oops}' and try again. \ (That will usually\cutpar \bugonpage A43, line 6 (07/24/14) \tenpoint\noindent keyboard, or that have been pre\"empted for formatting? \bugonpage A49, cummings quote (08/03/19) (delete the period at the end of the line) \bugonpage A66, line 3 from the bottom (08/26/17) \ninepoint Such displays of box contents will be discussed further in Chapters 12 and~27.\cutpar \bugonpage A105, lines 9--16 (01/16/21) \ddanger If you say \.{\char`\\vadjust\char`\{}$\langle\,$vertical mode material$\,\rangle$\.{\char`\}} within a paragraph, \TeX\ will use internal vertical mode to insert the specified material into the vertical list that encloses the paragraph, immediately after whatever line contained the position of the \.{\char`\\vadjust}. For example, you can say `\.{\char`\\vadjust\char`\{\char`\\kern1pt\char`\}}' to increase the amount of space between lines of a paragraph if those lines would otherwise come out too close together. \ (The \vadjust{\kern1pt}author did that in the current line, just to illustrate what happens.) \ Also, if you want to make sure that a page break will occur immediately after a certain line, you can say `\.{\char`\\vadjust\char`\{\char`\\eject\char`\}}' anywhere in that line. \bugonpage A122, lines 3--8 (11/24/19) \ninepoint\noindent \.{\char`\\count255}, \.{\char`\\dimen255}, \.{\char`\\skip255}, \.{\char`\\muskip255}, and \.{\char`\\toks255} are traditionally kept available for such purposes. Furthermore, plain \TeX\ reserves \.{\char`\\dimen0} to \.{\char`\\dimen9}, \.{\char`\\skip0} to \.{\char`\\skip9}, \.{\char`\\muskip0} to \.{\char`\\muskip9}, and \.{\char`\\box0} to \.{\char`\\box9} for ``scratchwork''; these registers are never allocated by the \.{\char`\\new...}\null\ operations. We have seen that \.{\char`\\count0} through \.{\char`\\count9} are special, and \.{\char`\\box255} also turns out to be special; so those registers should be avoided unless you know what you are doing. \bugonpage A155, line 8 from the bottom (01/17/21) \ninepoint\indent \.{\char`\\mathopen\char`\{\char`\\hbox\char`\{\char`\$\char`\\left\char`\#1}% $\langle\,$strut$\,\rangle$\.{\char`\\right.\char`\$\char`\}\char`\}} \bugonpage A155, the bottom six lines (12/10/18) \ninepoint\noindent dividual symbols; \.{\char`\\left}$\,\ldots\,$\.{\char`\\right} constructions are treated as ``inner'' subformulas, which means that they will be surrounded by additional space in certain circumstances. All other subformulas are generally treated as ordinary symbols, whether they are formed by \.{\char`\\overline} or \.{\char`\\hbox} or \.{\char`\\vcenter} or by simply being enclosed in braces. Thus, \.{\char`\\mathord} isn't really a necessary part of the \TeX\ language; instead of typing `\.{\char`\$1\char`\\mathord,234\char`\$}' you can get the same effect from `\.{\char`\$1\char`\{,\char`\}234\char`\$}'. \bugonpage A158, line 19 (12/10/18) \ninepoint\indent Inner\quad is an inner atom produced by `\.{\char`\\left}$\,\ldots\,$\.{\char`\\right}'; \bugonpage A170, lines 18 and 19 (12/10/18) \ninepoint\noindent subformulas delimited by \.{\char`\\left} and \.{\char`\\right} are treated as type~Inner. The following table is used to determine the spacing between pairs of adjacent atoms: \bugonpage A171, line 19 from the bottom (06/15/19) \ninepoint\noindent formula produces a result essentially equivalent to `\.{\char`\\left(}$\langle\,$subformula$\,\rangle$\.{\char`\\right)}', when\cutpar \bugonpage A215, line 16 from the bottom becomes two lines (10/13/20) \ninepoint \item\bull Just after a token such as \.{\char`\$}$_3$ that begins math mode, to see if another token of category 3 follows. \bugonpage A222, lines 21--23 (01/16/21) \ninepoint \halign{\indent#\hfil&\quad(see Chapter #)\hfil\cr \.{\char`\\hbox}$\langle\,$box specification$\,\rangle$% \.{\char`\{}$\langle\,$horizontal mode material$\,\rangle$\.{\char`\}}&12\cr \.{\char`\\vbox}$\langle\,$box specification$\,\rangle$% \.{\char`\{}$\langle\,$vertical mode material$\,\rangle$\.{\char`\}}&12\cr \.{\char`\\vtop}$\langle\,$box specification$\,\rangle$% \.{\char`\{}$\langle\,$vertical mode material$\,\rangle$\.{\char`\}}&12\cr } \bugonpage A222, lines 11--13 from the bottom (01/16/21) \ninepoint\noindent ter~15. The \.{\char`\\vsplit} operation is also explained in Chapter~15. In math modes an additional type of box is available: \.{\char`\\vcenter}$\langle\,$box specification$\,\rangle$% \.{\char`\{}$\langle\,$vertical mode material$\,\rangle$\.{\char`\}} (see Chapter~17). \bugonpage A232, line 14 (01/10/21) \ninepoint\noindent tabs outside; `\.{\char`\\global\char`\\settabs}' will not do what you might think it should. \bugonpage A233, lines 3--5 (04/27/15) \tenpoint\noindent Only two tabs are set in this case, because only two \.{\char`\&}'s appear in the sample line. \ (A sample line usually ends with~\.{\char`\&\char`\\cr}, as it does here, because text material between the last tab and \.{\char`\\cr} isn't used for anything.) \bugonpage A252, lines 5--7 (12/25/20) \ninepoint\noindent blank, and the footline is normally a centered page number, but you can specify any headline and footline that you want by changing the token lists \.{\char`\\headline} and \.{\char`\\footline}. For example, \bugonpage A253, lines 7--9 from the bottom (10/27/20) \ninepoint\indent \.{\char`\\everypar} or \.{\char`\\errhelp}, except that \TeX\ retains the begin-group symbol~`\.{\char`\{}' at the beginning and the end-group symbol~`\.{\char`\}}' at the end. These grouping characters help to keep the output routine from interfering with what \TeX\ was doing\cutpar \bugonpage A256, line 19 (08/28/15) \ninepoint\indent \tt \char`\\baselineskip=24pt \char`\\lineskiplimit=0pt \bugonpage A277, lines 9 and 10 from the bottom (08/26/17) \ninepoint\indent $\langle\,$hyphenation assignment$\,\rangle$\is \.{\char`\\hyphenation}$\langle\,$filler$\,\rangle$% \.{\char`\{}$\langle\,$hyphenations$\,\rangle$\.{\char`\}}\par \qquad \alt \.{\char`\\patterns}$\langle\,$filler$\,\rangle$% \.{\char`\{}$\langle\,$patterns$\,\rangle$\.{\char`\}} \bugonpage A286, bottom two lines {(and affecting the top lines of page 287)} (08/26/17) \ninepoint\noindent stands for zero or more \ commands other than \.{\char`\\setbox}, possibly with \. If the assignments are not followed by a \, where \ stands\cutpar \bugonpage A287, lines 11--17 (04/22/20) \ninepoint \textindent{$\bull$} \.{\char`\\discretionary}% \\\.\enskip A \ has the form `\\.{\char`\{}\\.{\char`\}}', where the material is processed in restricted horizontal mode and should contain only fixed-width things. More precisely, the horizontal list formed by each \ must consist only of characters, ligatures, kerns, boxes, and rules; there should be no glue or penalty items, etc. This command appends a discretionary item to the current list; see Chapter~14 for the meaning of a discretionary item. The space factor is not changed. \bugonpage A292, lines 8--10 (04/22/20) \ninepoint \textindent{$\bull$} \.{\char`\\discretionary}% \\\.\enskip This command has the same effect as in horizontal mode (see Chapter~25), but the third \ must produce an empty list. \bugonpage A299, line 11 from the bottom (11/01/20) \ninepoint\noindent is corrupted or was prepared for a different version of \TeX. \bugonpage A305, bottom line (06/30/20) \ninepoint\indent \tt \char`\\setbox0=\char`\\hbox\char`\{\char`\#1\char`\}% \char`\\advance\char`\\dimen0 by -\char`\\wd0 \char`\}\rm. \bugonpage A309, line 2 becomes two lines (12/06/20) \ninepoint\noindent represent text entered from the user's terminal, or with `\.{}', when they represent text inserted during error recovery). \bugonpage A316, lines 17 and 18 from the bottom (09/03/15) \ninepoint\noindent (The next line must also not be too tall.) Here \.{\char`\\specialstar} is a box of height zero and depth \.{\char`\\strutdepth}, and it puts an asterisk in the left margin: \bugonpage A320, lines 5--9 from the bottom (06/27/15) \ninepoint\noindent {\bf 17.21.}\enspace Assigning \.{\char`\\delcode\char`\`\char`\{} would not work to allow `\.{\char`\\left\char`\{}', because the brace has category~1 and isn't a legal \. Allowing brace delimiters would be a bad idea because it would mess up other constructions, such as arguments to macros, and components of alignments. Moreover, a user who gets away with `\.{\char`\\left\char`\{}' is likely to try also `\.{\char`\\bigl\char`\{}', which fails miserably. \bugonpage A326, line 12 (08/26/17) \ninepoint\noindent its natural width. The \.{\char`\\hbox} version also invokes \.{\char`\\everyhbox} and \.{\char`\\everymath}. \bugonpage A329, line 3 of answer 20.7 (05/15/19) \ninepoint\noindent the three tokens \.{!1}, \.{\char`\#2}, \.{[}$_1$; the \ consists of the six tokens \.{\char`\{}$_1$, \.{\char`\#}$_6$,\cutpar \bugonpage A329, line 6 of answer 20.7 (05/15/19) \ninepoint\noindent is otherwise irrelevant. Thus, `\.{\char`\\def\char`\\!!1\char`\#2\char `\#[\char`\{\char`\#\char`\#]!!\char`\#2]}' would produce an essentially\cutpar \bugonpage A329, line 5 from the bottom of answer 20.7 (05/15/19) \ninepoint\indent \.{!1<-x} \bugonpage A329, bottom line of answer 20.7 (05/15/19) \ninepoint\noindent final parameter in the parameter text; `\.{!1}' would have been rendered `\.{\char`\#1}'. \bugonpage A332, lines 13 and 14 (08/26/17) \ninepoint\noindent {\bf 21.10.}\enspace If you say `\.{\char`\{\char`\\let}\stretch \.{\char`\\the=0\char`\\edef}\stretch \.{\char`\\next}\stretch \.{\char`\{\char`\\write}\stretch \.{\char`\\cont}\stretch \.{\char`\{}\\.{\char`\}\char`\}\char`\\next}\stretch \.{\char`\}}', the \.{\char`\\write} will be exercuted after \.{\char`\\edef} expands everything except \.{\char`\\the}. \bugonpage A332, bottom line (11/15/19) \ninepoint\indent\quad \tt \char`\\+\char`\&\char`\{\char`\\bf end\char`\};\char`\\cr \ \char`\%\ note that the semicolon isn't bold \bugonpage A342, lines 12 and 13 (08/14/20) \tenpoint\noindent of plain \TeX\ format; but some of them are primitive (built in), such as `\.{\char`\\par}' (end of paragraph), `\.{\char`\\noindent}' (beginning of non-indented paragraph), and `\.{\char`\/}' (italic\cutpar \bugonpage A345, lines 10--13 from the bottom (06/27/15) \ninepoint\noindent Braces are used for grouping, when supplying arguments to macros; so they cannot also be used as math delimiters, or as arguments to macros such as \.{\char`\\big}. (One could change their catcodes to~12, and use some other pair of characters for grouping; but that would not be plain \TeX.) \bugonpage A346, lines 10--22 (11/24/19) \ninepoint\noindent number identification.) \ (2)~The registers \.{\char`\\count255}, \.{\char`\\dimen255}, \.{\char`\\skip255}, \.{\char`\\toks255}, and \.{\char`\\muskip255} are freely available in the same way. \ (3)~All assignments to the scratch registers whose numbers are 1,~3, 5, 7, and~9 should be \.{\char`\\global}; all assignments to the other scratch registers (0,~2, 4, 6, 8,~255) should be non-\.{\char`\\global}. \ (This prevents the phenomenon of ``save stack buildup'' discussed in Chapter~27.) \ (4)~Furthermore, it's possible to use any register in a group, if you ensure that \TeX's grouping mechanism will restore the register when you're done with the group, and if you are certain that other macros will not make global assignments to that register when you need it. \ (5)~But when a register is used by several macros, or over long spans of time, it should be allocated by \.{\char`\\newcount}, \.{\char`\\newdimen}, \.{\char`\\newbox}, etc. \ (6)~Similar remarks apply to input/output streams used by \.{\char`\\read} and \.{\char`\\write}, to math families used by \.{\char`\\fam}, to sets of hyphenation rules used by \.{\char`\\language}, and to insertions (which require \.{\char`\\box}, \.{\char`\\count}, \.{\char`\\dimen}, and \.{\char`\\skip} registers all having the same number).\looseness=-1 \bugonpage A347, line 6 (06/30/20) \ninepoint\noindent \tt \char`\\def\char`\\wlog\char`\{\char`\\immediate\char`\\write-1 \char`\} \ \char`\%\ this will write on log file (only) \bugonpage A347, line 10 (11/24/19) \ninepoint\noindent \tt \char`\\outer\char`\\def\char`\\newmuskip\char`\{\char`\\alloc@3% \char`\\muskip\char`\\muskipdef\char`\\@cclv\char`\} \bugonpage A347, line 14 (11/24/19) \ninepoint\noindent \tt \char`\\outer\char`\\def\char`\\newtoks\char`\{\char`\\alloc@5% \char`\\toks\char`\\toksdef\char`\\@cclv\char`\} \bugonpage A350, lines 15 and 16 from the bottom (01/17/21) \ninepoint\noindent format; it shouldn't cost much for people to acquire all the fonts of plain \TeX\ in addition to the ones that they really want. Second, it is desirable on many computer systems to\cutpar \bugonpage A364, line 5 from the bottom (01/14/21) \ninepoint\noindent \tt \char`\\def\char`\\fmtversion\char`\{3.1415926535\char`\} \ \char`\%\ identifies the current format \bugonpage A370, lines 11 and 12 (08/26/17) \ninepoint\noindent close as possible to the ASCII conventions. \ (b)~Make sure that codes \oct{041}--\oct{046}, \oct{060}--\oct{071}, \oct{136}, \oct{141}--\oct{146}, and \oct{160}--\oct{171} are present and that each unrepresentable in-\cutpar \bugonpage A373, lines 21 and 22 (01/17/21) \ninepoint\noindent and \.{\char`\\if...\char`\\fi} tests, as well as special operations like \.{\char`\\the} and \.{\char`\\input}, while the latter category includes the primitive commands listed in Chapters~24--26. The expansion of\cutpar \bugonpage A375, bottom three lines (06/30/20) \ninepoint\noindent |$$\generaldisplay$$| to be invoked, with |\eq| defined to be $\alpha$. Furthermore, when an equation number~$\beta$ is present, it should be stored in |\eqn|, and the test |\ifeqno| should be true. In such cases |\ifleqno| should distinguish |\leqno| from |\eqno|. Here\cutpar \bugonpage A398, lines 4 and 5 (08/26/17) \ninepoint\indent |\setbox2=\lastbox \setbox\footins=\vbox{\box2}|\par \smallskip\noindent since |\lastbox| will be the result of\/ |\rigidbalance|, which is an hbox. \bugonpage A407, line 5 from the bottom (06/30/20) \ninepoint\noindent\quad | \interlinepenalty5000\def\par{\endgraf\penalty5000 }}| \bugonpage A413, line 11 from the bottom (05/14/19) \ninepoint\indent The computer file |texbook.tex| that generated {\sl The \TeX book\/} begins with a\cutpar \bugonpage A418, line 4 (05/14/19) \ninepoint\noindent \TeX\ commands that look like this in the file |texbook.tex|: \bugonpage A420, line 11 (06/30/20) \ninepoint\noindent |\def\bull{\vrule height.9ex width.8ex depth-.1ex \relax} % square bullet| \bugonpage A423, line 16 (06/30/20) \ninepoint\noindent | \vrule height6pt depth2pt width0pt \relax} % a strut for \insert\margin| \bugonpage A445, lines 10--14 (12/10/18) \ninepoint \textindent{\bf 15e.} Enclose the vbox that was constructed in Rule 15c or 15d by delimiters $(\lambda,\rho)$ whose height plus depth is at least $\sigma_{20}$, if $C>T$, and at least $\sigma_{21}$ otherwise. Shift the delimiters up or down so that they are vertically centered with respect to the axis. Replace the generalized fraction by an Ord atom whose nucleus is the resulting sequence of three boxes ($\lambda$, vbox, $\rho$). Go to rule~19. \bugonpage A446, the bottom three lines of Rule 19 become four lines (01/10/21) \ninepoint\noindent atom and the right boundary item to a Close atom. The entire resulting list now becomes the nucleus of an Inner atom. \ (All of the calculations in this step are done with $C$ equal to the starting style of the math list; style items in the middle of the list do not affect the style of the right boundary item.) \bugonpage A454, lines 17 and 18 from the bottom (04/13/20) \ninepoint\noindent of the process; the trial word consists of all the letters found in admissible items, up to a maximum of~63. Notice that all of these letters are in font~$f$. \bugonpage A458 and following, selected amendments to the index (01/18/21) \eightpoint |[1]| (progress report), 23, $\underline{119}$.\par |\aa| ( \aa\ ), {\it52}, $\underline{356}$.\par |\AA| ( \AA\ ), {\it52}, $\underline{356}$.\par \, $\underline{287}$, 292.\par \, $\underline{276}$, 279, 280.\par \, 278, 285, 287.\par integral signs, {\sl see\/} |\int|, |\oint|, |\smallint|.\par \, 287, 289--293.\par |\null|, 311, {\it312}, {\it316}, {\it332}, {\it335}, $\underline{351}$, {\it354}, {\it360}--{\it362}, {\it419}.\par |\o| ( \o\ ), {\it52}, $\underline{356}$.\par |\O| ( \O\ ), {\it52}, $\underline{356}$.\par programs, for computers, 38, 165, {\it234}.\par repeating templates, {\sl see\/} periodic preambles.\par replacement text, {\it200}--{\it204}, 212, 280, 300, 329.\par right delimiters, {\sl see\/} closings.\par struts, $\underline{82}$, 125, 131, 142, 155, 178, 245--247, 255, 329, 416, 422, 423.\par \, 278, 280--282, 290. % volume B \def\\#1{\hbox{\it#1\/\kern.05em}} % italic type for identifiers \def\dts{\mathrel{.\,.}} % double dot, used only in math mode \bugonpage Bv {(formerly Bvii)}, bottom two lines (01/15/21) \eightpoint\noindent all of those changes. I~now believe that the final bug was discovered on 22 October 2020 and removed in version 3.141592653. % on 12 January 2021 The finder's fee has converged to \$327.68. \hsize=35pc \bugonpage B2, line 10 from the bottom (01/15/21) \ninepoint\noindent\hskip10pt {\bf define} $\\{banner}\equiv\hbox{\tt\char'23}$% {\tt This\]is\]TeX,\]Version\]3.141592653\char'23}\quad $\{\,$printed when \TeX\ starts$\,\}$ \bugonpage B4, line 8 of \S7 (04/02/17) \tenpoint\noindent diagnostic information for \.{\char`\\tracingparagraphs}, \.{\char`\\tracingpages}, and \.{\char`\\tracingrestores}. \bugonpage B21, lines 33 and 34 (04/02/17) \def\Oct#1{\hbox{\rm\char'23\kern-.2em\it#1\/\kern.05em}} % octal constant \tenpoint\noindent $[\Oct{41}\to\Oct{46},\Oct{60}% \to\Oct{71},\Oct{136},\Oct{141}\to\Oct{146},\Oct{160}\to\Oct{171}]$ must be printable. Thus, at least 80 printable characters are needed. \bugonpage B28, lines 3 and 4 (04/02/17) \tenpoint\noindent not serious since we assume that this part of the program is system dependent. \bugonpage B28, line 2 from the bottom (04/02/17) \ninepoint\noindent\quad {\bf var} $k$: $0\dts23$;\quad$\{\,$index to current digit; we assume that $\vert n\vert<10^{23}\,\}$ \bugonpage B35, line 2 of \S83 becomes two lines (06/27/20) \ninepoint\noindent\quad {\bf loop begin} \\{continue}: {\bf if} $\\{interaction}\ne\\{error\_stop\_mode}$ {\bf then return};\par \noindent\qquad \\{clear\_for\_error\_prompt}; \ \\{prompt\_input}(\.{"?\]"}); \bugonpage B36, line 11 of \S84 (07/03/20) \ninepoint\noindent\quad \.{"E"}: {\bf if} $\\{base\_ptr}>0$ {\bf then if} $\\{input\_stack}[\\{base\_ptr}].\\{name\_field}\ge256$ {\bf then} \bugonpage B36, line 5 of \S85 becomes two lines (07/03/20) \ninepoint\noindent\quad {\bf if} $\\{base\_ptr}>0$ {\bf then}\par \noindent\qquad {\bf if} $\\{input\_stack}[\\{base\_ptr}].\\{name\_field}\ge256$ {\bf then} \\{print}(\.{"E\]to\]edit\]your\]file."} \bugonpage B40, line 5 from the bottom (08/07/20) \ninepoint\noindent\qquad (\.{"Try\]to\]insert\]an\]instruction\]for\]me\](e.g.,\]% \char`\`I\char`\\showlists\char`\'),"}) \bugonpage B58, lines 2 and 3 of \S136 (10/11/20) \tenpoint\noindent the values corresponding to `\.{\char`\\hbox\char`\{\char`\}}'. The \\{sub\_type} field is set to \\{min\_quarterword}, for historic reasons that are no longer relevant. \bugonpage B88, line 16 (10/22/20) \tenpoint\noindent The mode is temporarily set to zero while processing \.{\char`\\write} texts. \bugonpage B102, lines 3 and following of \S241 (12/11/20) \tenpoint\noindent information, something special is needed. The program here simply assumes that suitable values appear in the global variables \\{sys\_time}, \\{sys\_day}, \\{sys\_month}, and \\{sys\_year} (which are initialized to noon on 4 July 1776, in case the implementor is careless). \smallskip \ninepoint\noindent {\bf procedure} \\{fix\_date\_and\_time};\par \noindent\quad{\bf begin} $\\{sys\_time}\gets12\ast60$; \ $\\{sys\_day}\gets4$; \ $\\{sys\_month}\gets7$; \ $\\{sys\_year}\gets1776$;\quad $\{\,$self-evident truths$\,\}$\par \noindent\quad$\\{time}\gets\\{sys\_time}$;\quad $\{\,$minutes since midnight$\,\}$\par \noindent\quad$\\{day}\gets\\{sys\_day}$;\quad$\{\,$day of the month$\,\}$\par \noindent\quad$\\{month}\gets\\{sys\_month}$;\quad$\{\,$month of the year$\,\}$\par \noindent\quad$\\{year}\gets\\{sys\_year}$;\quad$\{\,$Anno Domini$\,\}$\par \noindent\quad{\bf end}; \bugonpage B103, replacement for \S246 (12/11/20) \tenpoint\noindent {\bf 246.}\quad Of course we had better declare a few more global variables, if the previous routines are going to work. \smallskip \ninepoint\noindent $\langle\,$Global variables {\sevenrm\kern.5em13}$\,\rangle+\equiv$\par \noindent\\{old\_setting}: $0\dts\\{max\_selector}$;\par \noindent\\{sys\_time}, \\{sys\_day}, \\{sys\_month}, \\{sys\_year}: \\{integer}; \quad$\{\,$date and time supplied by external system$\,\}$ \goodbreak \bugonpage B122, lines 9 and 10 of \S291 (10/12/20) \tenpoint\noindent\quad The enclosing \.{\char'173} and \.{\char'175} characters of a macro definition are omitted, but an output routine will be enclosed in braces. \bugonpage B143, lines 2, 3, 4 become four lines (01/15/17) \tenpoint\noindent routines that should be aborted, but we can sketch the ideas here: For a runaway definition or a runaway balanced text, we will insert a right brace; for a runaway preamble, we will insert a special \.{\char`\\cr} token and a right brace; and for a runaway argument, we will set \\{long\_state} to \\{outer\_call} and insert \.{\char`\\par}. \bugonpage B188, line 8 (04/02/17) \ninepoint\noindent {\bf function} \\{str\_toks}$(b:\\{pool\_pointer})$: \\{pointer};\quad $\{\,$converts \\{str\_pool}$[b\dts\\{pool\_ptr}-1]$ to a token list$\,\}$ \bugonpage B192, line 17 (10/22/20) \ninepoint\noindent\quad {\bf label} \\{found}, \\{continue}, \\{done}, \\{done1}, \\{done2}; \bugonpage B192, line 3 of \S474 (10/22/20) \ninepoint\noindent\qquad {\bf begin} \\{continue}: \\{get\_token};\quad$\{\,$set \\{cur\_cmd}, \\{cur\_chr}, \\{cur\_tok}$\,\}$ \bugonpage B193, line 4 of \S476 (05/20/20) \ninepoint\noindent\quad {\bf if} $\\{cur\_tok}<\\{left\_brace\_limit}$ {\bf then} \bugonpage B193, line 10 of \S476 becomes two lines (10/22/20) \ninepoint\noindent\qquad \\{help2}(\.{"I\char`\'m\]going\]to\]ignore\]the\]\#\]sign\]you\]just\]used,"})\par \noindent\qquad (\.{"as\]well\]as\]the\]token\]that\]followed\]it."}); \\{error}; {\bf goto} \\{continue}; \bugonpage B196, line 5 from the bottom (02/17/18) \ninepoint\noindent\qquad\quad \\{help1}(\.{"This\]\char`\\read\]has\]unbalanced\]braces."}); $\\{align\_state}\gets1000000$; $\\{limit}\gets0$; \\{error}; \bugonpage B199, lines 1--3 of \S494 (10/25/20) \tenpoint\noindent {\bf 494.} \ \ Here is a procedure that ignores text until coming to an \.{\char`\\or}, \.{\char`\\else}, or \.{\char`\\fi} at the current level of $\.{\char`\\if}\ldots\.{\char`\\fi}$ nesting. After it has acted, \\{cur\_chr} will indicate the token that was found, but \\{cur\_tok} will not be set (because this makes the procedure run faster). \bugonpage B214, lines 2--6 of \S536 (12/11/20) \ninepoint\noindent\quad {\bf begin} \\{wlog}(\\{banner}); \\{slow\_print}(\\{format\_ident}); \\{print}(\.{"\]\]"}); \\{print\_int}(\\{sys\_day}); \\{print\_char}(\.{"\]"});\par \noindent\quad $\\{months}\gets\.{\char`\'JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC\char`\'}$;\par \noindent\quad {\bf for} $k\gets3\ast\\{sys\_month}-2$ {\bf to} $3\ast\\{sys\_month}$ {\bf do} \\{wlog}(\\{months}[$k$]);\par \noindent\quad \\{print\_char}(\.{"\]"}); \\{print\_int}(\\{sys\_year}); \\{print\_char}(\.{"\]"}); \\{print\_two}(\\{sys\_time} {\bf div} 60); \\{print\_char}(\.{":"});\par \noindent\quad \\{print\_two}(\\{sys\_time} {\bf mod} 60); \bugonpage B214, line 2 of \S537 becomes two lines (10/29/20) \tenpoint\noindent command is being processed. Beware: For historic reasons, this code foolishly conserves a tiny bit of string pool space; but that can confuse the interactive `\.E' option. \bugonpage B214, bottom line (10/29/20) \ninepoint\noindent {\bf if} $\\{name}=\\{str\_ptr}-1$ {\bf then} \ $\{\,$conserve string pool space (but see note above)$\,\}$ \bugonpage B219, lines 18--20 of \S545 (09/19/19) \tenpoint\noindent so-called boundary character of this font; the value of \\{next\_char} need not lie between \\{bc} and~\\{ec}. If the very last instruction of the \\{lig\_kern} array has $\\{skip% \_byte}=255$, there is a special ligature/kerning program for a boundary character at the left, beginning at location $256\ast\\{op\_byte}+$\cutpar \bugonpage B282, line 1 {(and change lines 20--23 accordingly)} (04/02/17) \tenpoint\noindent {\bf 682.} Each portion of a formula is classified as Ord, Op, Bin, Rel, Open, Close, Punct, or Inner, for\cutpar \bugonpage B299, line 4 from the bottom of \S722 (10/06/20) \ninepoint\noindent\qquad\quad {\bf begin} \\{char\_warning}(\\{cur\_f}, \\{qo}(\\{cur\_c})); $\\{math\_type}(a)\gets\\{empty}$; $\\{cur\_i}\gets\\{null\_character}$; \bugonpage B318, lines 16 and 17 of \S761 become one (03/25/19) \ninepoint\noindent \\{fraction\_noad}: $s\gets\\{fraction\_noad\_size}$; \bugonpage B333, line 5 of \S793 becomes two lines (01/10/20) \ninepoint\noindent\quad $\\{cur\_loop}\gets\\{link}(\\{cur\_loop})$; $\\{link}(p)\gets\\{new\_glue}(\\{glue\_ptr}(\\{cur\_loop}))$;\par \noindent\quad $\\{subtype}(\\{link}(p))\gets\\{tab\_skip\_code}+1$; \bugonpage B348, insert a new line after line 5 of \S826 (01/15/17) \ninepoint\noindent\qquad {\bf stat if} $\\{tracing\_paragraphs}>0$ {\bf then} \\{end\_diagnostic}(\\{true}); \ {\bf tats} \bugonpage B348, insert a new line to be the seventh line after the previous change (01/15/17) \ninepoint\noindent\qquad {\bf stat if} $\\{tracing\_paragraphs}>0$ {\bf then} \\{begin\_diagnostic}; \ {\bf tats} \bugonpage B377, line 6 (10/31/20) \ninepoint\noindent \\{hn}: $0\dts64$; \ $\{\,$the number of positions occupied in \\{hc}; not always a \\{small\_number}$\,\}$ \bugonpage B417, mini-index (04/02/17) \eightpoint\noindent The entry `\\{height}, \S981.' here and on many later odd-numbered pages should be `$\\{height}=\rm macro$, \S135.' \bugonpage B522, line 3 of \S1306. (10/25/20) \tenpoint\noindent to be in the range $a\le x\le b$. System error messages should be suppressed when undumping. \bugonpage B533, lines 5--8 of \S1333. (10/15/20) \tenpoint\noindent loop. (Actually there's one way to get error messages, via \\{prepare\_mag}; but that can't cause infinite recursion.)\par \noindent\quad If \\{final\_cleanup} is bypassed, this program doesn't bother to close the input files that may still be open. \bugonpage B533, line 12 of \S1333. (11/29/20) \ninepoint\noindent\quad {\bf begin} $\langle\,$Finish the extensions{\sevenrm\kern.5em1378}$\,\rangle$; $\\{new\_line\_char}\gets-1$; \bugonpage B534, line 6 of \S1335. (11/29/20) \ninepoint\noindent\quad {\bf begin} $c\gets\\{cur\_chr}$; {\bf if} $c\ne1$ {\bf then} $\\{new\_line\_char}\gets-1$; \bugonpage B537, line 18 of \S1338 becomes two lines (10/05/20) \ninepoint\noindent\quad {\bf begin} \\{clear\_terminal};\par \noindent\quad {\bf loop} \bugonpage B537, lines 11 and 12 from the bottom of \S1338 become three lines (04/02/17) \ninepoint\noindent\qquad\qquad {\bf begin goto} \\{breakpoint};\par \noindent\qquad\qquad\quad$\{\,$go to every declared label at least once$\,\}$\par \noindent\qquad\quad\\{breakpoint}: $m\gets0$; \.{@\char`\{\char`\'BREAKPOINT\char`\'@\char`\}} \bugonpage B600, the bottom five lines (05/14/19) \tenpoint\noindent they occupy in a typical production system (executable code size for dark blocks, global data size for light blocks). In this way the chart indicates a total of about $12\times22=264${\ninerm K} bytes of memory, plus $12\times10=120${\ninerm K} for the dynamic memory region not shown explicitly. The dynamic memory is often considerably larger in practice, because it is desirable to accommodate large macro packages and large pages. % volume C \hsize=29pc \def\\#1{\hbox{\it#1\/\kern.05em}} % italic type for identifiers \def\dashto{\mathrel{\hbox{-\thinspace-\kern-.05em}}} \def\ddashto{\mathrel{\hbox{-\thinspace-\thinspace-\kern-.05em}}} \def\tension{\mathop{\rm tension}} \def\controls{\mathop{\rm controls}} \def\and{\,{\rm and}\,} \bugonpage Cx, line 4 from the bottom (06/14/20) \count255=1 \def\diamondleaders{\global\advance\count255 by 1 \ifodd\count255 \kern-10pt \fi \leaders\hbox to 20pt{\ifodd\count255 \kern13pt \else\kern3pt \fi .\hss}} \line{\strut \hbox to\parindent{\bf\hbox to 1em{\hss20}\hss}% \rm More About Macros\diamondleaders\hfil\hbox to 2em{\hss175}} \bugonpage C39, lines 10 and 11 become three lines (07/04/20) \tenpoint\noindent that has already been designed. All you'll see is `|(io.mf| |The| |letter| |O| |[79])|' or possibly only `|(io.mf| |[79])|', followed by~`|*|'. Now the fun starts: You should type \bugonpage C68, lines 9, 28, 35, 36, 38 (11/11/17) \ninepoint \halign{\indent\hbox to 160pt{\tt#\hfil}&\tt#\hfil\cr uniformdeviate -100&-36.1628\cr z slanted 1/6&(0.16667y+x,y)\cr (a,b)zscaled(3,4)&(-4b+3a,3b+4a)\cr (a,b)zscaled dir 30&(-0.5b+0.86603a,0.86603b+0.5a)\cr (a,b)dotprod(3,4)&4b+3a\cr } \bugonpage C72, lines 4--18 (07/16/20) \ninepoint\noindent \beginsyntax \is \alt \alt[(][)] \alt[normaldeviate] \alt[length] \alt[length] \alt[length] \alt[angle] \alt[xpart] \alt[ypart] \alt \is[/] \alt \is[,]}> \alt[\char'133]% [,][\char'135] \endsyntax \bugonpage C76, lines 8--16 from the bottom (11/11/17) \newdimen\longesteq \setbox0=\hbox{\indent$z_{12}-z_{11}=z_{14}-z_{13}$\quad} \longesteq=\wd0 \tenpoint\noindent \hangindent\longesteq \hangafter0 tom edge of the type. \ (With plain \MF's {\bf beginchar} each character has a ``bounding box'' that runs from $(0,h)$ at the upper left and $(w,h)$ at the upper right to $(0,-d)$ and~$(w,-d)$ at the lower left and lower right; variable $d$ represents the depth of the type. The values of $w$, $h$, and~$d$ might change from character to character, since the individual pieces of type need not have the same size in a computer-produced font.) \bugonpage C80, line 14 (06/13/20) \tenpoint\indent \\{penpos}\(\,\thinspace\). \bugonpage C83, line 16 (06/13/20) \ninepoint\indent |### 0.5a=-c-0.5b+1.5| \bugonpage C83, line 19 (06/13/20) \ninepoint\noindent the only dependent variable is now $d$, which equals $0.5c+0.75b+0.75$. \ (This is\cutpar \bugonpage C96, line 13 from the bottom (10/31/20) \tenpoint\noindent illustrates the use of $u\0$, $s\0$, $\\{ht}\0$, \\{logo\_pen}, \\{leftstemloc}, $o$, \\{xgap}, and \\{barheight}: \bugonpage C106, lines 19--21 (07/03/20) \ninepoint\noindent pixels. \ (Some typesetting systems use both of these device-dependent amounts to alter their current position on a page, just after typesetting each character. Other systems, like typical |dvi| software associated with \TeX, assume that $\\{chardy}=0$ but use \\{chardx}\cutpar \bugonpage C113, lines 5--11 from the bottom (07/20/20) \def\cycle{\hbox{\rm cycle}} \ninepoint\noindent \begindisplay $s\0:=5\\{pt}\0$; \ {\bf define\_pixels}$(s)$; \ \% side of the square\cr $z_1=(0,0)$; \ $z_2=(s,0)$; \ $z_3=(0,s)$; \ $z_4=(s,s)$;\cr {\bf for} $k=1$ {\bf upto} 4: $z[k+4]=z[k]+({2\over3}s,{1\over3}s)$; \ {\bf endfor}\cr {\bf pickup pencircle} scaled $.4\\{pt}$; \ {\bf draw} $z_5\dashto z_6\dashto z_8\dashto z_7\dashto \cycle$;\cr {\bf pickup pencircle} scaled $1.6\\{pt}$; \ {\bf erase draw} $z_2\dashto z_4\dashto z_3$;\cr {\bf pickup pencircle} scaled $.4\\{pt}$; \ {\bf draw} $z_1\dashto z_2\dashto z_4\dashto z_3\dashto \cycle$;\cr {\bf for} $k=1$ {\bf upto} 4: {\bf draw} $z[k]\dashto z[k+4]$; \ {\bf endfor}.\cr \enddisplay \bugonpage C114, line 7 (07/20/20) \ninepoint\indent {\bf for} $k=0$ {\bf upto} 4: \ $z[k]=\\{center}+(\\{radius},0)$ rotated$(90+{360\over5}k)$; \ {\bf endfor} \bugonpage C128, lines 13 and 14 (06/13/20) \ninepoint\noindent changed. Plain \MF\ has a {\bf tensepath} operation that does this. For example, {\bf tensepath}~\\{unitsquare}~$=$ $(0,0)\ddashto(1,0)\ddashto(1,1)\ddashto(0,1)\ddashto\cycle$. \bugonpage C136, lines 18 and 19 (07/17/20) \ninepoint\noindent only about 0.28 with respect to the initial and final directions; since \MF\ insists that tensions be at least~0.75, this anomalous path could never have arisen if the control\cutpar \bugonpage C155, line 7 (10/07/20) \tenpoint\indent \\is\\\thinspace|end| \bugonpage C160, lines 7--9 (06/25/20) \ninepoint\noindent might produce a transcript that includes the following diagnostic information: \begintt rotatedaround(EXPR0)(EXPR1)-> shifted-(EXPR0)rotated(EXPR1)shifted(EXPR0) \endtt \bugonpage C165, lines 5--7 from the bottom (11/11/17) \ninepoint\noindent (i.e., parameters in parentheses), then we name zero or one or two undelimited parameters. Then comes an `$=$'~sign, followed by the replacement text, and {\bf enddef}. The `$=$'~sign might also be~`$:=$'\thinspace; both mean the same thing. \bugonpage C171, lines 18--20 (08/16/20) \ninepoint\indent Chapter~14's syntax rules for \, via \. A pair expression is not considered to be of type {\bf path} unless the path interpretation is the only~possibility. \bugonpage C176, line 7 from the bottom (07/09/20) \ninepoint\indent \quad {\bf if} |@#|$(\\{x\_})\colon\ \\{tx\_} \ \hbox{\bf else}\colon\ \\{fx\_}\ \hbox{\bf fi}$ :=\ \\{x\_}\thinspace; {\bf endfor} \bugonpage C180, line 3 from the bottom (06/24/20) \ninepoint\indent `$=$' or `$:=$' following {\bf let}. \bugonpage C187, line11 from the bottom (07/12/20) \ninepoint\indent\qquad \alt|substring|\thinspace\\thinspace|of|\thinspace \ \bugonpage C189, line 14 (06/13/20) \ninepoint\noindent `|! |' and followed by~`|.|', followed by lines of context as in \MF's normal error\cutpar \bugonpage C200, line 12 from the bottom (08/27/20) \ninepoint\indent $y_1=y_2=\\{good.y}(.5[-d,h]+1.1\\{pt})$; \bugonpage C202, line 17 from the bottom (06/13/20) \ninepoint\noindent command, and it works only when the \\{penpos} angle is~0. If the \\{penpos} command is\cutpar \bugonpage C210, bottom eight lines, and top ten lines of page C211 (07/16/20) \ninepoint\noindent \beginsyntax \is\alt \alt \alt \alt[normaldeviate] \alt[(][)] \alt[begingroup][endgroup] \alt[length]\alt[length] \alt[length]\alt[length] \alt[ASCII]\alt[oct]\alt[hex] \alt\alt \alt[angle] \alt[turningnumber]\alt[totalweight] \alt \alt[directiontime][of] \is[/] \alt \is[,]}> \alt[\char'133]% [,][\char'135] \endsyntax \bugonpage C214, line 6 becomes two lines (07/17/20) \ninepoint\noindent \beginsyntax \is \alt[pencircle] \endsyntax \bugonpage C214, line 6 from the bottom (07/12/20) \ninepoint\noindent \beginsyntax \alt[substring][of] \endsyntax \bugonpage C217, lines 20--25 (10/07/20) \ninepoint\noindent \beginsyntax \is[end] \alt[dump] \is\alt[;] \is\alt \alt\alt\alt \alt\alt\alt \endsyntax \bugonpage C219, line 25 (05/25/20) \ninepoint\noindent to see which of its subscripts and suffixes have occurred. For example, if you're\cutpar \bugonpage C224, lines 7--9 from the bottom (12/21/18) \tenpoint\indent |y4r=-0.9848thinn+259.00049|\par |x4r=-0.08682thinn+144|\par |y4=-0.4924thinn+259.00049| \bugonpage C226, lines 9 and 10 (11/01/20) \ninepoint\noindent This means that the preloaded base you have specified cannot be used, because it is corrupted or was prepared for a different version of \MF\kern-.03em. \bugonpage C228, line 27 (06/19/20) \ninepoint\indent |l.94 endfor| \bugonpage C228, line 4 from the bottom (07/12/20) \ninepoint\noindent might want to review now.) \ You probably also have a |proof| mode diagram: \bugonpage C234, line 4 of answer 4.6 (07/20/20) \ninepoint\indent {\bf for} $k=1$ {\bf upto} 6: $z[k]'=.2[z[k],z_0]$; {\bf endfor} \bugonpage C241, line 2 (11/11/17) \ninepoint\indent |\mode=cheapo; input cheaplogo10| \bugonpage C242, line 11 of answer 13.7 (07/20/20) \ninepoint\indent {\bf for} $k=1$ {\bf upto} 4: $z[k+4]=z[k]+({2\over3}s,{1\over3}s)$; \ {\bf endfor} \bugonpage C243, lines 7 and 8 (11/08/15) \ninepoint\indent \indent {\bf draw} subpath$(k,k+1)$ of \\{star}; {\bf cullit};\par\indent \indent {\bf undraw} subpath$(k+2,k+3)$ of \\{star} {\bf withpen} \\{eraser}; {\bf cullit}; \bugonpage C243, line 3 of answer 13.11 (06/17/20) \ninepoint\indent {\bf def overdraw expr} $c$ = {\bf begingroup save} \\{region}; \bugonpage C243, lines 12--16 of answer 13.11 (05/24/20) \ninepoint\noindent \begindisplay {\bf beginchar}$(\hbox{\tt"M"},1.25\\{in}\0,.5\\{in}\0,0)$; \ {\bf pickup pencircle} scaled .4\\{pt};\cr $z_1=(20,-13)$; \ $z_2=(30,-6)$; \ $z_3=(20,1)$; \ $z_4=(4,-7)$;\cr \indent $z_5=(-12,-13)$; \ $z_6=(-24,-4)$; \ $z_7=(-15,6)$;\cr {\bf path} $M$; $M=(\\{origin}\dts z_1\dts z_2\dts z_3\dts z_4\dts z_5\dts z_6\dts z_7\dts$\cr \indent$\\{origin}\dts -z_7\dts -z_6\dts -z_5\dts -z_4\dts -z_3\dts -z_2\dts -z_1\dts\cycle)$\cr \enddisplay \bugonpage C246, line 2 of answer 14.13 (08/16/20) \ninepoint\noindent path $z_0\dashto z_1$ is equivalent to `$z_0\dts \controls1/3[z_0,z_1]\and2/3[z_0,z_1]\dts z_1$', and the\cutpar \bugonpage C247, line 1 of answer 15.5 (06/13/20) \ninepoint\noindent \quad{\bf 15.5.}\enspace {\bf beginchar}$(126,25u\0,\\{h\_height}\0+\\{border}\0,0)$; \ |"Dangerous left bend"|; \bugonpage C247, replacement for answer 15.7 (07/21/20) \ninepoint\noindent \quad{\bf 15.7.}\enspace Replace lines 10 and 11 by \begindisplay {\bf pickup pencircle} scaled 3/4\\{pt} yscaled 1/3 rotated $-60$;\cr {\bf draw} ($z_1\ldots p$) transformed $t$;\cr {\bf addto} \\{currentpicture} {\bf also} \\{currentpicture}\cr \qquad rotatedaround$\bigl((.5w,.5h)$ yscaled \\{aspect\_ratio}$,-180\bigr)$;\cr \enddisplay \bugonpage C249, line 1 of answer 18.9 (08/02/20) \ninepoint\noindent \quad{\bf 18.9.}\enspace {\bf beginchar}\kern1pt(|"H"|$,13u\0,"ht"\0,0)$; \ {\bf pickup} \\{broad\_pen}; \bugonpage C249, line 11 of answer 18.9 (08/02/20) \ninepoint\indent {\bf filldraw} $\\{bot\_serif\_edge}_4$ \bugonpage C250, line 4 of answer 19.1 (04/19/20) \ninepoint\noindent because it saves a wee bit of time and because `;'\ often belongs before {\bf endfor}. \bugonpage C250, replacement for answer 19.3 (07/12/20) \ninepoint\noindent \quad{\bf 19.3.}\enspace Yes, if and only if $n-{1\over2}$ is an even integer. \ (Because ambiguous values are rounded upwards.) \bugonpage C251, replacement for answer 22.1 (07/12/20) \ninepoint\noindent \quad{\bf 22.1}\enspace (a) If and only if $n$ is an integer between 0 and 255. (b) If and only if $s$ is a string of length~1. \bugonpage C254, lines 10--13 from the bottom become five lines (06/26/20) \ninepoint\noindent \begintt ? H I found no right delimiter to match a left one. So I've put one in, behind the scenes; this may fix the problem. |null ? \endtt \bugonpage C260, the ``line'' after line 3 (06/14/20) \def\bb{$\,\left\{\vcenter\bgroup\halign\bgroup\hfil##\hfil\cr} \def\ee{\crcr\egroup\egroup\right\}\,$} \tenpoint\noindent \bb|font_size|\cr|font_slant|\cr|font_normal_space|\cr |font_normal_stretch|\cr|font_normal_shrink|\cr|font_x_height|\cr |font_quad|\cr|font_extra_space|\ee \bb|=|\cr\noalign{\kern-2pt}|:=|\cr\noalign{\kern-2pt}\\ee \; \ \bb|ligtable|\\cr|charlist|\\cr|extensible|\\cr |fontdimen|\\cr|headerbyte|\\ee;\kern-10pt \bugonpage C261, lines 16 and 17 from the bottom (06/14/20) \tenpoint\noindent \bb|proofrule|\cr|screenrule|\ee|(|\|,|\|)|; \ |makegrid(|\|)(|\|)|;\smallskip\noindent |proofrulethickness| \; \ |proofoffset| \. \bugonpage C266, lines 19 and 20 (07/04/20) \ninepoint\noindent You can say either `|incr|~|x|' or `|incr|~|(x)|', within an expression; but neither of them are valid statements by themselves. \bugonpage C269, line 11 (01/10/21) \ninepoint\indent |\smode="specmode"; mag=|\|; input |\ \bugonpage C277, lines 15--19 (03/06/17) \ninepoint\noindent |def openit = openwindow currentwindow from origen % and please correct|\par \noindent | to (screen_rows,screen_cols) at (-50,300) enddef; % "(-50,300)" too|\par \noindent |def showit_ = display currentpicture inwindow currentwindow enddef;|\par \noindent |def showit = openit; let showit=showit_; showit enddef; % first time only|\par \kern3pt\hrule\medskip\noindent Plain \MF\ has several other terse commands similar to `{\bf openit}' and `{\bf showit}': \bugonpage C279, line 1 (11/11/17) \ninepoint\noindent | blacker:=.1; % make pens a teeny bit blacker| \bugonpage C289, line 20 (10/07/20) \ninepoint\indent |if {{(pair x) cand x>(0,0)}}: A else: B fi.| \bugonpage C291, line 18 (07/24/20) \ninepoint\indent | save u_; setu_ u; let switch_ = if; if false: enddef.| \bugonpage C292, line 10 from the bottom (10/23/20) \ninepoint\noindent be known by saying `{\bf if} known $(p-q)$: $p=q$ {\bf else}:~{\bf false fi}'; transforms could be handled\cutpar \bugonpage C293, lines 13 and 14 from the bottom (10/27/20) \ninepoint\noindent $f(-1)$ is false! When $c\rightarrow0$, the quantity $a^3+b^3$ approaches $-\infty$ when $c$~is positive, $+\infty$ when $c$~is negative. An attempt to `\\{solve} $f(1,-1)$' will divide by zero and come\cutpar \bugonpage C295, line 2 (07/04/20) \ninepoint\noindent `interpolate $(1,1)\dts(3,2)\dts(15,4)$ of~7' the approximate value 3.37. \bugonpage C299, bottom four lines of code become five (08/06/20) \ninepoint\noindent \begintt primarydef t Bernshtein nn = begingroup save r; r = begingroup for n=nn downto 2: for k=1 upto n-1: u_[[[k]]]:=t[[[u_[[[k]]],u_[[[k+1]]] ]]]; endfor endfor u_[[[1]]] endgroup; numeric u_[[[]]]; r endgroup enddef; \endtt \bugonpage C299, line 5 after the code becomes two lines (08/06/20) \ninepoint\noindent brackets are nested inside of brackets. However, the auxiliary variables `|u_[[[|$k$|]]]|' must not remain independent at the end. \bugonpage C305, lines 14--18 (07/08/20) \ninepoint\noindent |width_adj#:=0pt#; % width adjustment for certain characters|\par \noindent |serif_fit#:=0pt#; % extra sidebar near lowercase serifs| \vskip-3pt\noindent\qquad\vdots\par\noindent |low_asterisk:=false; % should the asterisk be centered at the axis?|\par \noindent |math_fitting:=false; % should math-mode spacing be used?| \bugonpage C317, line 21 becomes two lines (11/11/17) \ninepoint\noindent \beginsyntax \alt[::]\alt[\\\\:] \is\[:] \endsyntax \bugonpage C318, lines 10--16 from the bottom (11/11/17) \ninepoint\noindent \beginsyntax \alt \is[extensible] \is[,][,][,] \endsyntax Notice that a \ can appear in a {\bf ligtable}, {\bf charlist}, or {\bf extensible} command. These appearances are mutually exclusive: No code may be used more than once as a label. Thus, for example, a character with a ligature/kerning program cannot also be {\bf extensible}, nor can it be in a {\bf charlist} (except as the final item). \bugonpage C333, line 29 (10/25/19) \ninepoint\noindent | "if charcode>0:currentpicture:=currentpicture scaled mg;fi;"| \bugonpage C333, bottom two lines become one (11/11/17) \ninepoint\noindent | if unknown scale: scale := max(1,round(pixels_per_inch/300)); fi| \bugonpage C339, line 3 (05/21/20) \ninepoint\noindent ing `\char'31', `\char'32', `\char'33', and~`\char'34') and the uppercase letters (including `\char'35', `\char'36', and~`\char'37') are\cutpar \bugonpage C341, line 14 from the bottom (11/11/17) \ninepoint\noindent prints the |\table| and the |\text|; ^|\bigtest| gives you the works, plus a mysterious word\cutpar \bugonpage C345 and following, selected amendments to the index (01/20/21) \eightpoint *|,| (comma), 57, 72, 73, 129, 155, 165--167, 171, 211--213, 218, 317, 318.\par `A', 10--11, 163, 164, 248, 302--303.\par \, 118, $\underline{220}$.\par bell-shaped distribution, $\underline{183}$, 251.\par |black|, 270, 332--333.\par \ and \, $\underline{317}$.\par concatenation, of paths, {\it70}--{\it71}, {\it123}, 127--129, $\underline{130}$, 137, {\it245}, {\it266}.\par \quad of strings, {\it69}, 73, 84--85, $\underline{187}$, {\it278}, {\it286}, {\it312}.\par *|directiontime|, {\it135}, $\underline{\it136}$, 211, 245, 265, {\it298}.\par distance, 76, 84, {\sl see also\/} |length|.\par |dotprod|, {\it68}--{\it69}, 178, {\it238}, 265.\par efficiency, 39, 99, 116, 141, 144, 147, 228, 230, 234, 244, 264, 265, 277, 291, 297, 298.\par empty option in {\bf for\/} list, 171, $\underline{172}$, {\it299}.\par forbidden tokens, 173, $\underline{218}$--$\underline{219}$, 286.\par *|from|, $\underline{191}$, 220, {\it252}, {\it277}, {\it312}.\par Giotto di Bondone, 139.\par independent variables, $\underline{81}$--$\underline{83}$, 88, 224, 226, 299.\par |\init|, $\underline{337}$, 342.\par internal quantities, 54--55, 88, 218, 262, 265--266.\par *|inwindow|, $\underline{191}$, 220, {\it277}.\par \, $\underline{118}$, 220.\par |labels|, {\it107}, $\underline{274}$, 327--328.\par *|length|, {\it66}, {\it69}, 72, 210, 238.\par *|ligtable|, {\it97}, {\it305}--{\it306}, $\underline{316}$--$\underline{317}$.\par loops, 169, 171--173, 179, 226--227, 259, 290--291, 299.\par `N', 184--185, 302--303.\par \, 72, $\underline{211}$.\par |o|, {\it23}, {\it34}, $\underline{93}$, 197, 200, 204, 240, 302.\par `O', 32--37, 161, 199, 302--303.\par overshoot, 23, 34, 93, 197, 200, 204, 302.\par |penpos|, {\it26}--{\it29}, 37, 80, {\it103}, {\it162}, $\underline{273}$, 310.\par pens, 21--29, 147--152, 297--298.\par *|rotated|, {\it21}--{\it22}, {\it25}, 27, 44, {\it68}, 73, {\it107}, {\it114}, {\it117}, $\underline{141}$, 213, {\it238}.\par |rule|, 274, 328.\par *|scaled|, {\it21}--{\it23}, {\it68}, 73, $\underline{141}$, 213, 244, 291.\par *|showstopping|, 211, 219, {\it227}, 230, {\it262}.\par string expressions, {\it69}, 187--189, 258, 286.\par \, $\underline{171}$, 236.\par sum, of vectors, 9, {\it68}.\par |test.mf|, 311--313.\par \TeX, 1, 34, 40, 91, 96, 98, 101--103, 315, 336--343, 361.\par text arguments, 219, 288--291, 299.\par |.tfm|, 39, 315--321, 333, 335.\par *|to|, $\underline{191}$, 220, {\it252}, {\it277}, {\it312}.\par undelimited suffix parameters, $\underline{167}$, 176, 266, 270.\par |undraw|, 113, 118, 120, {\it242}, $\underline{271}$.\par |unitsquare|, {\it116}, 123--124, 128, 132, 136, $\underline{263}$.\par *|unknown|, $\underline{170}$, 210.\par unknown quantities, nonnumeric, 84--85, 143.\par values, disappearance of, 56, 83, 88, 156--157, 177--178, 218, 239, 299.\par \, 165, $\underline{178}$.\par *|xscaled|, {\it21}--{\it22}, {\it68}, 73, $\underline{141}$, 213, 244, 291.\par % Volume D \def\\#1{\hbox{\it#1\/\kern.05em}} % italic type for identifiers \def\to{\mathrel{.\,.}} % double dot, used only in math mode \bugonpage Dv, line 16 (01/16/21) \tenpoint\noindent \kern12.5mm I believe that the final bug in \MF\ was discovered on January\cutpar \bugonpage Dv, bottom two lines (01/16/21) \eightpoint\noindent corporates all of those changes. I~now believe that the final bug was discovered on 03 July 2020 and removed in version 2.71828182. % on 16 January 2021 The finder's fee has converged to \$327.68. \hsize=35pc \bugonpage D2, last line of \S2 (01/15/21) \ninepoint\noindent $$\hbox{{\bf define} $\\{banner}\equiv\.{\char`\'This\]is\]METAFONT,\]Version\]2.71828182\char`\'}$\quad $\{\,$printed when \MF\ starts$\,\}$}$$ \bugonpage D14, line 1 of \S30 (05/05/14) \tenpoint\noindent {\bf 30.} \quad The \\{input\_ln} function brings the next line of input from the specified file into available\cutpar \bugonpage D21, line 8 of \S47 (10/11/20) \ninepoint\noindent\quad $g$: \\{str\_number};\quad$\{\,$the string just created$\,\}$ \bugonpage D27, lines 3 and 4 of \S61 (04/02/17) \tenpoint\noindent is not serious since we assume that this part of the program is system dependent. \bugonpage D28, line 7 (04/02/17) \ninepoint\noindent\quad {\bf var} $k$: $0\dts23$;\quad$\{\,$index to current digit; we assume that $\vert n\vert<10^{23}\,\}$ \bugonpage D32, line 2 of \S78 becomes two lines (06/27/20) \ninepoint\noindent\quad {\bf loop begin} \\{continue}: {\bf if} $\\{interaction}\ne\\{error\_stop\_mode}$ {\bf then return};\par \noindent\qquad \\{clear\_for\_error\_prompt}; \ \\{prompt\_input}(\.{"?\]"}); \bugonpage D32, line 11 of \S79 (07/03/20) \ninepoint\noindent\quad \.{"E"}: {\bf if} $\\{file\_ptr}>0$ {\bf then if} $\\{input\_stack}[\\{file\_ptr}].\\{name\_field}\ge256$ {\bf then} \bugonpage D33, line 5 of \S80 (07/03/20) \ninepoint\noindent\quad {\bf if} $\\{file\_ptr}>0$ {\bf then}\par \noindent\qquad {\bf if} $\\{input\_stack}[\\{file\_ptr}].\\{name\_field}\ge256$ {\bf then} \\{print}(\.{"E\]to\]edit\]your\]file."} \bugonpage D37, line 9 of \S93 (08/07/20) \ninepoint\noindent\qquad (\.{"Try\]to\]insert\]an\]instruction\]for\]me\](e.g.,\]% \char`\`I\]show\]x;\char`\'),"}) \bugonpage D82, line 2 from the bottom (09/19/19) \ninepoint\noindent\quad {\bf define} $\\{boundary\_char}=41$\quad$\{\,$the boundary character for ligatures$\,\}$ \bugonpage D85, lines 3 and 4 of \S194 {(and \S194 actually moves to page D86)} (12/11/20) \tenpoint\noindent information, something special is needed. The program here simply assumes that suitable values appear in the global variables \\{sys\_time}, \\{sys\_day}, \\{sys\_month}, and \\{sys\_year} (which are initialized to noon on 4 July 1776, in case the implementor is careless). \bugonpage D85, the final six lines of \S194 {(and \S194 actually moves to page D86)} (12/11/20) \ninepoint\noindent {\bf procedure} \\{fix\_date\_and\_time};\par \noindent\quad{\bf begin} $\\{sys\_time}\gets12\ast60$; \ $\\{sys\_day}\gets4$; \ $\\{sys\_month}\gets7$; \ $\\{sys\_year}\gets1776$;\quad $\{\,$self-evident truths$\,\}$\par \noindent\quad$\\{internal}[\\{time}]\gets\\{sys\_time}\ast\\{unity}$;\quad $\{\,$minutes since midnight$\,\}$\par \noindent\quad$\\{internal}[\\{day}]\gets\\{sys\_day}\ast\\{unity}$;\quad$\{\,$day of the month$\,\}$\par \noindent\quad$\\{internal}[\\{month}]\gets\\{sys\_month}\ast\\{unity}$;\quad$\{\,$month of the year$\,\}$\par \noindent\quad$\\{internal}[\\{year}]\gets\\{sys\_year}\ast\\{unity}$;\quad$\{\,$Anno Domini$\,\}$\par \noindent\quad{\bf end}; \bugonpage D86, replacement for \S196 (12/11/20) \tenpoint\noindent {\bf 196.}\quad Of course we had better declare a few more global variables, if the previous routines are going to work. \smallskip \ninepoint\noindent $\langle\,$Global variables {\sevenrm\kern.5em13}$\,\rangle+\equiv$\par \noindent\\{old\_setting}: $0\dts\\{max\_selector}$;\par \noindent\\{sys\_time}, \\{sys\_day}, \\{sys\_month}, \\{sys\_year}: \\{integer}; \quad$\{\,$date and time supplied by external system$\,\}$ \bugonpage D97, line 2 of \S221 (05/26/17) \tenpoint\noindent the definition of attribute nodes) that it is convenient to let $\\{info}(p)=0$ stand for `\.{[]}'. \goodbreak \bugonpage D148, line 7 (06/12/18) \tenpoint\noindent but the $\log n$ factor is buried in our implicit restriction on the maximum raster size.) The\cutpar \bugonpage D237, line 5 of \S513 (05/26/17) \ninepoint\noindent\quad {\bf for} $n\gets0$ {\bf to} $\\{n1}-\\{n0}-1$ {\bf do} $\\{env\_move}[n]\gets\\{mm0}$; \bugonpage D250, line 2 of \S534 (05/26/17) \tenpoint\noindent direction $\bigl(\\{right\_u}(p),\\{left\_v}(q)\bigr)$; and there's a line of length $\ge\\{delta}$ from vertex~$q$ to vertex~$r$,\cutpar \bugonpage D296, line 11 (06/23/20) \tenpoint\noindent \\{name} points to the \\{eqtb} address of the macro being expanded, if the current token list\cutpar \bugonpage D324, line 13 of \S713 (12/20/20) \ninepoint\noindent\qquad\quad \\{help2}(\.{"After\]\char`\`exitif\]\char`\'\]I\]expect\]to\]see\]a\]% semicolon."}) \bugonpage D326, line 5 from the bottom (06/23/20) \ninepoint\noindent\qquad\qquad $\{\,$invokes a user-defined sequence of commands$\,\}$ \bugonpage D334, lines 1 and 2 of \S742 (10/25/20) \tenpoint\noindent {\bf 742.} \ Here is a procedure that ignores text until coming to an {\bf elseif}, {\bf else}, or {\bf fi} at the current level of {\bf if}$\,\ldots\,${\bf fi} nesting. After it has acted, \\{cur\_mod} will indicate the token that was found. \bugonpage D339, line 4 of \S757 (06/16/20) \tenpoint\noindent\quad (A user who tries some shenanigan like `{\bf for} $\ldots$ {\bf let} {\bf endfor}' will be foiled by the \\{get\_symbol}\cutpar \bugonpage D351, lines 2--7 of \S790 become five lines (12/11/20) \ninepoint\noindent\quad {\bf begin} \\{wlog}(\\{banner}); \\{slow\_print}(\\{format\_ident}); \\{print}(\.{"\]\]"}); \\{print\_int}(\\{sys\_day}); \\{print\_char}(\.{"\]"});\par \noindent\quad $\\{months}\gets\.{\char`\'JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC\char`\'}$;\par \noindent\quad {\bf for} $k\gets3\ast\\{sys\_month}-2$ {\bf to} $3\ast\\{sys\_month}$ {\bf do} \\{wlog}(\\{months}[$k$]);\par \noindent\quad \\{print\_char}(\.{"\]"}); \\{print\_int}(\\{sys\_year}); \\{print\_char}(\.{"\]"}); \\{print\_two}(\\{sys\_time} {\bf div} 60); \\{print\_char}(\.{":"});\par \noindent\quad \\{print\_two}(\\{sys\_time} {\bf mod} 60); \bugonpage D352, line 2 of \S793 becomes two lines (10/29/20) \tenpoint\noindent command is being processed. Beware: For historic reasons, this code foolishly conserves a tiny bit of string pool space; but that can confuse the interactive `\.E' option. \bugonpage D352, line 5 from the bottom (10/29/20) \ninepoint\noindent {\bf if} $\\{name}=\\{str\_ptr}-1$ {\bf then} \ $\{\,$conserve string pool space (but see note above)$\,\}$ \bugonpage D354, line 2 from the bottom (07/29/20) \tenpoint\noindent $\\{cur\_type}=\\{path\_type}$ means that \\{cur\_exp} points to the first node of a path; nobody else points\cutpar \bugonpage D469, lines 18--20 of \S1093 (09/19/19) \tenpoint\noindent so-called boundary character of this font; the value of \\{next\_char} need not lie between \\{bc} and~\\{ec}. If the very last instruction of the \\{lig\_kern} array has $\\{skip% \_byte}=255$, there is a special ligature/kerning program for a boundary character at the left, beginning at location $256\ast\\{op\_byte}+$\cutpar \bugonpage D469, line 30 of \S1093 (01/15/21) \tenpoint\noindent tional halt; no ligature or kerning command is performed. \bugonpage D471, lines 20 and 21 (08/07/20) \ninepoint\noindent \\{param}: {\bf array} $[1\dts\\{max\_font\_dimen}]$ {\bf of} \\{scaled};\quad$\{\,${\bf fontdimen} parameters$\,\}$\par\noindent \\{np}: $0\dts\\{max\_font\_dimen}$;\quad$\{\,$the largest {\bf fontdimen} parameter specified so far$\,\}$ \bugonpage D474, line 2 from the bottom (08/07/20) \ninepoint\noindent\quad\qquad \\{help1}(\.{"A\]colon\]should\]follow\]a\]headerbyte\]or\]fontdimen\]location."}); \\{back\_error}; \bugonpage D508, line 3 of \S1189. (10/05/20) \tenpoint\noindent to be in the range $a\le x\le b$. System error messages should be suppressed when undumping. \bugonpage D516, line 6 (10/15/20) \tenpoint\noindent\quad If \\{final\_cleanup} is bypassed, this program doesn't bother to close the input files that may still be open. \bugonpage D519, line 17 (01/15/21) \ninepoint\noindent\quad \\{fix\_date\_and\_time}; $\\{init\_randoms}(\\{sys\_time}+\\{sys\_day}*\\{unity})$; \bugonpage D520, line 18 of \S1212 becomes two lines (10/05/20) \ninepoint\noindent\quad {\bf begin} \\{clear\_terminal};\par \noindent\quad {\bf loop} \bugonpage D520, lines 11 and 12 from the bottom of \S1212 become three lines (04/02/17) \ninepoint\noindent\qquad\qquad {\bf begin goto} \\{breakpoint};\par \noindent\qquad\qquad\quad$\{\,$go to every declared label at least once$\,\}$\par \noindent\qquad\quad\\{breakpoint}: $m\gets0$; \.{@\char`\{\char`\'BREAKPOINT\char`\'@\char`\}} \bugonpage D566, the bottom five lines (05/14/19) \tenpoint\noindent they occupy in a typical production system (executable code size for dark blocks, global data size for light blocks). In this way the chart indicates a total of about $8\times22=176${\ninerm K} bytes of memory, plus $8\times15=120${\ninerm K} for the dynamic memory region not shown explicitly. The dynamic memory is often considerably larger in practice, because it is desirable to accommodate large macro packages and large pictures. % volume E \hsize=29pc \newbox\shorthyf \setbox\shorthyf=\hbox{-\kern-.05em} \mathchardef\period=`\. {\catcode`\-=\active \global\def-{\copy\shorthyf\mkern3.9mu} \catcode`\.=\active \global\def.{\period\mkern3mu}} \def\8#1{\mathrel{\mathcode`\.="8000 \mathcode`\-="8000 #1\unkern}} % `..' and `--' \bye