function SumS=FpexRlxGamSin(al,del,a,b);  
% sumS fr FPEX relaxation wth IC DEP k=2n={2,4,6,8,10,..} 
% indefinte integral to X (x^2*al-1)*sin(del*x) dx del=m*pi/(b-a)
% . for matix dimensions D. Bakewell 17:45 Su/15/8/1999
format long;
ComIncGam2alA=gamma(2*al)*(1-gammainc(-i*a*del,2*al));
ComIncGam2alB=gamma(2*al)*(1-gammainc(-i*b*del,2*al));
exgadif=exp(i*al*pi)*(ComIncGam2alA-ComIncGam2alB);
SumS=(del^(-2*al))*(imag(exgadif))