Software/Algorithim to use in data fitting

Hi everyone, I am recently working on a project and have some questions about the computing part in it. So the situation is, I have a formula of a probability distribution and a set of market data points. I want to testify that the set of data points fits the theoretical PDF. But I am not sure which software is the best to use. The formula I got is quite complicated(an integral of some hyperbolic functions with complex number) and I think C++ can't really do the plotting efficiently. I looked into Maple but it took too long to plot the graph and also I don't know if maple have the function to fit data points on a graph. So now I am thinking about to learn Matlab to do it but I don't know will the level of the coding be too advanced to learn. So I wonder if anyone have suggestions about the software/algorithim I should use on this case?
Any input will be appreciated, thank you.
thanks for the advice,
so i spent half day to learn Matlab and found some problems now
I have a integrand of two variables x and y. I have to do an integration over y to get an expression depends on x only and then plot it against x.
Now the problem is the integrand is too complicated that i cannot use the 'int' command but must use a 'quad' instead,
but since the expression includes the variable x, the quad does not allow me to do a numerical integration.
So is there any ways to do an integration over a two variables function w.r.t one variables only?
thank you
As far as i understood you want to vary the interval in which x lies and keep a fixed interval of y.Why not calculate the whole integral every time with different values of x and that fixed y 0r am i interpreting it wrong?
that should work, but then I have to change the values of x many times to get the plot, so is there any ways to do it will one/few command only?
Thanks for your help