Function quadgk can numerically integrate for infinity. It is Gauss-Kronrod quadrature. For example:

[q,errbnd] = quadgk(@(x)exp(-x.^2),-inf,inf,'RelTol',1e-8,'AbsTol',1e-12)

The result is 1.7725

You might be interested in this file also:

http://www.mathworks.com/matlabcentral/fileexchange/32

my function is @(x)gammainc(x,m)*(1-gammainc(kx,n) where I input the values of m, n and k. Only i have to integrate this function ranges from -infinity to +infinity w.r.t x. I am doing like your way. But I cant.

I think that your integrand is infinite, so this is first problem. Also, your statement is incorrect, should be:

@(x)gammainc(x,m).*(1-gammainc(k*x,n))

Can you paste error here?

Ok.......I tried it....Is their any alternative way...

In my opinion you can't integrate your function.

For more help, you can ask your question on the official MATLAB forum:

http://www.mathworks.com/matlabcentral/answers/

Can you paste error here? This line I cant follow you sir..

Thanks you sir...This will help in may research work...I am sending a request in facebook

" Can you paste error here? This line I cant follow you sir.. "

It is easier to help you when we can see an error message from MATLAB