text: how to decompose the formula? dear all : i have one question with the following formula : x is discrete fq:= sum (re(x)*ln(re(x))), i have value q1:=sum(r1(x)*ln(r1(x))) and q2:=sum(r2(x)*ln(r2(x))), also i know the relation of re(x) , r1(x) and r2(x). re(x)= convolution of r1(x) and r2(x); i tried to use definition and decompose the fq from current space , but it cannot work. the ln prohibit that method. is there any way i can use q1and q2 to express the fq? thanks for any hint. bin no idea.