function SumC=FpexRlxKIntCos(x,n,del)
% sumC for FPEX relaxation wth IC DEP k=2n={2,4,6,8,10,..} 
% indefinte integral to X (x^-2n)*cos(del*x) dx del=m*pi/(b-a)
% n-2 sum D.Bakewell 16:20 Mo/9/8/1999
format long;
n2sumS=0;
n1sumC=0;
nsi=0;
n2term=0;
if n>=2;
   for jc=1:1:n-1; % actually j=0:1:n-2
      j=jc-1;
      n2term=n2term+((-1)^j)*gamma(2*j+2)/((del*x)^(2*j+1));
   end
n2sumS=-sin(del*x)*n2term*(del^(2*n-1))*((-1)^(n-1))/(del*x*gamma(2*n));   
elseif n<2;
   n2sumS=0;
end
% n-1 sum
n1term=0;
if n>=1
   for jc=1:1:n; % actually j=0:1:n-1
      j=jc-1;
      n1term=n1term+((-1)^(j+1))*gamma(2*j+1)/((del*x)^(2*j));
   end
n1sumC=cos(del*x)*n1term*(del^(2*n-1))*((-1)^(n-1))/(del*x*gamma(2*n));      
elseif n==0
   n1sumC=0
end
% NOTE: i=sqrt(-1)
nsi=-imag(expint(i*del*x))*(del^(2*n-1))*((-1)^(n+1))/gamma(2*n);
n2sumS;
n1sumC;
nsi;
SumC=n2sumS+n1sumC+nsi;