Integrals



When I try to do the following integral: 

assume(a>1);
declare(a, noninteger);
assume(s>0);
assume(H>0);
 
f: c^(a-1)/s^a*(exp(-c/s))/gamma(a);
pdenom: minfactorial(makefact(fullratsimp(integrate(c*f, c, 0, inf))));
p: fullratsimp(c*f/pdenom);
 
integrate(c*p*H/(c+H), c, 0, inf);


I get 

(%i13)                    integrate(-----, c, 0, inf)
                                    H + c
                                   inf
                                  /     a + 1   - c/s
                        - a - 1   [    c      %e
                       s        H I    -------------- dc
                                  ]        H + c
                                  /
                                   0
(%o13)                 ---------------------------------
                                  a gamma(a)


However, when I do it in Maple it works and I get: 

 g0 := int(gd, x=0..infinity);
                                      GAMMA(a~)
                          g0 := ----------------------
                                     a~                        (-a~)
                                s~   gamma(a~) s~


How can I get Maxima to do the integral? 

Thank you,
Lindsay 



Lindsay Keegan
PhD Candidate
Theoretical Biology Lab
Department of Biology
McMaster University