cmath

[cHup]

i'm confused about "cmath"
what's the main points cmath?

[modoran]

Do you mean this ?
http://www.cplusplus.com/reference/clibrary/cmath/

I don't understand your question.

[Peter87]

cmath is a header that contains a lot of useful math functions.

[Chervil]

You can do a lot of calculations without using the cmath library.
For example:

    int x = 5;
    int y = x * x;    // y is x squared 

but what if we want something like this:

    int x = 25;
    int y = √x;    // y should be the square root of x 

That doesn't work, as there is no operator for square root. Instead, we use a library function:

    double x = 25.0;
    double y = sqrt(x);

And the same applies for many other functions, some common, such as sin or log, and others maybe less obvious, but still useful in their own way.