Lære Standard Math | Introduction

In addition to the +, -, *, /, and % operations, we can perform many more mathematical operations using functions from the <cmath> library. Here is a table of the most used ones:

All of this is part of the standard math library. To use it, you need to include the appropriate header file. You can do this by including either cmath or math.h.

include.h


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#include <cmath>
// OR
#include <math.h>

The main difference between cmath and math.h lies in their purpose and usage. cmath is part of the C++ standard library, designed specifically for C++ and requiring the std namespace (e.g., std::sqrt()), while math.h comes from the C standard library, uses the global namespace (e.g., sqrt()), and is compatible with C++.

main.cpp


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#include <iostream>
#include <cmath>

int main()
{
    std::cout << "cos(0) = "     << cos(0)      << std::endl;
    std::cout << "sin(0) = "     << sin(0)      << std::endl;
    std::cout << "tan(pi/4) = "  << tan(M_PI/4) << std::endl;
    std::cout << "exp(1) = "     << exp(1)      << std::endl;
    std::cout << "log(e) = "     << log(M_E)    << std::endl;
    std::cout << "pow(2, 3) = "  << pow(2, 3)   << std::endl;
    std::cout << "sqrt(4) = "    << sqrt(4)     << std::endl;
    std::cout << "cbrt(8) = "    << cbrt(8)     << std::endl;
    std::cout << "ceil(7.8) = "  << ceil(7.8)   << std::endl;
    std::cout << "floor(7.8) = " << floor(7.8)  << std::endl;
    std::cout << "round(7.8) = " << round(7.8)  << std::endl;
}

Note

Constants M_PI and M_E for value of π (3.1415...) and e (2.7183...) are also defined in the <cmath> library.

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