##change / AIUQ	0.5.2
 * fixed typo for method name in SAM class
 * update get_isf function
 * add argument A_neg in SAM class that controls modification for negative A(q), options from  ('abs','zero'), with absolute value as the default value
 * output estimated A(q) and B using AIUQ method
 * change the formal of arXiv to include doi
##change / AIUQ 0.5.1
 * implement simulation and estimation of the anisotropic process through aniso_simulation() and aniso_SAM()