习题1 matlab">syms t z; Gam=int(exp(-t)*t^(z-1),t,0,inf); I1=subs(Gam,z,sym(1/2)), I2=subs(Gam,z,sym(3/2)), I3=subs(Gam,z,sym(5/2)), I4=subs(Gam,z,sym(7/2))