See the articles "The trapezoidal rule of integration" and "A statistical application of numerical integration: The area under an ROC curve".   A SAS/IML module is provided. If you don't have SAS/IML, then you can use the DIF function in the DATA step to compute the widths of the trapezoids. ... View more

Also, what does a--c mean? That doesn't have meaning in the context you're using it in.    You probably want either the max( of a--c) or sum(). I'm guessing max based on context.  I would suggest finding max and looping up to that value to set G vars to 1.    Array gv(4) g1-G4 (4*0);   max_count = max(a,b,c);   do i=1 max_count; g(i) = 1; end;  ... View more