Hi Roger,
I tried that already, but MATLAB is giving me that in gammainc(1nu, A), A should be real and nonnegative.
A=0.5 is real but negative, so the ERROR
I just needed to evaluate it. I had a anaother function, whose integral is given in terms of the exponential intergarl.
thanks FOR THE RESPONSE
ROY
Roger Stafford" <ellieandrogerxyzzy@mindspring.com.invalid> wrote in message <i41isa$ksb$1@fred.mathworks.com>...
> "sitiroy Roy" <sitiroy@gmail.com> wrote in message <i41dst$2st$1@fred.mathworks.com>...
> > Hi,
> >
> > I am trying to integrate a generalized exponential integral E_nu(z)
> > where my nu=0.7 and z=0.5
> >
> > Can I do it in MATLAB?
> >
> > or is there any package by which I can do it?
> >
> > roy
>         
> I believe E_p(x) can be evaluated in terms of the incomplete gamma function and matlab has that function for real values of x.
>
> E_p(x) = int(exp('x*t)/t^p','t',1,inf)
> = x^(p1)*int('exp(s)/s^p','s',x,inf)
>
> where the substitution s = x*t is made. This latter integral can be found from matlab's gammainc with the 'upper' option. (Remember, though, that gammainc is normalized.)
>
> It wasn't clear whether you wanted to evaluate E_nu(z) or integrate it. Your use of the letter z suggests you want it with complex values, but the value 0.5 you assigned it is real. I believe matlab's incomplete gamma function can only use real arguments.
>
> Roger Stafford
