It's more likely you are going to need a number of languages during your studies. I studied computer science and have a phd in network engineering which has a heavy mathematical background.
You definately need a language like C++ or C# which are quite similar in their syntax style (wouldn't recommend Visual Basic even if it's practically the same code as C#). However, you are going to reach a point where you'd need to develop a complex mathematical function to keep developing in those languages, as they do not have everything by default.
You might be able to purchase mathematical libraries for C#/C++ however you would need to be certain that they are suitable for your needs and efficiently implemented.
Matlab is a great piece of software to cover your mathematical needs. Its latest version allows you to create C# wrappers for your .M scripts so you can continue using C# code while at the same time leveraging Matlab's mathematical potential.
Lastly, if you are going towards something that requires intence computational needs then there is something else you might need to consider. Development on one of the new NVidia Graphics cards that support CUDA. CUDA is basically a language that allows you to use the Graphics Card's processing power to do the calculations on it instead of the CPU. CUDA is similar to C, and you can create a library to invoke *again* by your C# code. (This is basically the reason I don't suggest VB, because this way your coding style will remain consistent). CUDA transforms your pc into a mini super computer (provided you program it correctly).
I write a lot of simulations and I am using a combination of the above mentioned technologies. The time spent learning them, is definately worth the time spent running simulations and developing.
Good luck mate.