Integrals which cant be solved

Dear fellows,

I sometimes work with some problematic functions, so I have question.

For example, I have simple Gaussian function a*exp(-x^2).

Now I need to solve integral int( sqrt(a*exp(-x^2)-En), 'x' ).

And after that I receive report:

Warning: Explicit integral could not be found.

My question is general, so not just for this function.

How to solve these problems? Is there some way to approximate

function like Gaussian, or all these stuff I have to solve

numerically?

If it is so, which numerically approach you recommend me for these

problems?

With best regards,

Nikola

Answer 1

[G A]

http://www.mathworks.co.uk/help/techdoc/ref/trapz.html

http://www.mathworks.co.uk/help/techdoc/ref/quad.html