creating distributions in mathematica -

I have a function that I know for distribution of multivariate (x, y), and numeric stability in mathematics There are issues when I make marginal distribution. For example, marginalization with Y gives the following yield: 0.e ^ (154.88-0.5x ^ 2)

Since I know that the result should be a distribution, I just e ^ (- 5x ^ 2) and rearranging yourself Alternatively, it would be better if the math took me a multivariate function and somehow specified it as a probability distribution.

Still, does anyone know how to apply both of the above solutions in the program?

OK, here's an example of what I mean. Suppose I have the following 2D distribution:

  district = 3.045975040844157 'E ^ (- (x ^ 2/2) - y ^ 2/2) (-1 + E ^ (- 1 `(x + 0.1` y) unit stap [x + 0.1` y]) ^ 2  

and i

  integrated [district, y , -Infinity, Infinity}]  

Mathematica does not provide an answer, or at least does not do anything on my computer Suggestion:

Edit: Ok, so it actually does, but with 4 GB rams, I take 5 minutes on my Intel i5 ... I'm still hoping Do not have been made in the delivery of Gnitika (although it seems to be only one variable to be the same) and their random Rilel [district]. The best I could expect if Mathematics would allow me to specify this 2D function as a distribution, and call RandomRealVector [dist].