function xdet=fpexdet(xb,nu,al,a,b);
% fpexdet is determinant for PFE normalised D.Bakewell 26th July 1999
% normalised = ((a^al)*(b^al)*Beta^2) factor taken out
aB=a*xb;
bB=b*xb;
%Term1A=((1-al)/a)*besselj(-nu,aB)+(xb/2)*(besselj(-1-nu,aB)-besselj(1-nu,aB));
%Term2A=((1-al)/a)*besselj(nu,aB)+(xb/2)*(besselj(-1+nu,aB)-besselj(1+nu,aB));
%Term1B=((1-al)/b)*besselj(-nu,bB)+(xb/2)*(besselj(-1-nu,bB)-besselj(1-nu,bB));
%Term2B=((1-al)/b)*besselj(nu,bB)+(xb/2)*(besselj(-1+nu,bB)-besselj(1+nu,bB));
%xdet=(a^al)*(b^al)*(Term1A*Term2B-Term2A*Term1B);
factr=double((a^al)*(b^al)*(xb^2));
xdet=factr*double(besselj(1-nu,bB)*besselj(nu-1,aB)-...
   besselj(1-nu,aB)*besselj(nu-1,bB));