cmath header confusion

Question

What is the namespace for math functions? Global or std?

Consider cos function. It has 3 overloads. But there is also legacy cos from math.

Answer 1

If you are using C++ you can rely on the function overloading.

There are three version of cos:

double cos (      double x );
float cos (       float x );
long double cos ( long double x );

But if you are using only C or you want portabilty only the double version of this function exists with this name. The float function is cosf.