Question

I am making a project that will use mathematic computations a lot. Also I want to be able to simply change the implementation of real numbers. Let’s say between float, double, my own implementation and gmplib float types.

So far I thouht of two ways:

1. I create a class “Number” which will interface with the rest of the program.

2. I typedef the arithmetic type and write global functions to interface with the rest of the program.

The first choice seems to be more elegant, but the second seems to have less overhead. Is there a third better choice? Also I am worried by the elementary mathematical functions such as sine, cosine, exp… I figured out that to make the switching easy, I should implement them as templates, but my implementations are hopelessly slow.

I am generally new to programming in C++. I was brought up in the comfortable Matlab and Mathematica environments, where I did not have to worry about such things.

Answer 1

Templates are the way I have done this. it makes it easy to specialize what must be specialized, and provides a good way to reuse implementations when it applies to multiple types.

The number type can be done, but it’s actually not simple to do right and introduces some restrictions (compared to templates).

Multiple types are just hopelessly complex, if you want something even close to fast, accurate, and simple to maintain. You’d likely end up using templates to implement these correctly if you were to create a global typedef.

Templates provide all the power, control, and flexibility you would need, and they will be faster than the alternatives posted (technically, #2 could be as fast if you resorted to… templates).