#NEWLINE# def fdiff( self , argindex = 1 ) : #NEWLINE# #INDENT# if ( argindex == 1 ) : #NEWLINE# #INDENT# z = self . args [ 0 ] #NEWLINE# return ( ( ( - 2 ) / sqrt ( S . Pi ) ) + ( ( 2 * z ) * _erfs ( z ) ) ) #NEWLINE# #UNINDENT# else : #NEWLINE# #INDENT# raise ArgumentIndexError ( self , argindex )