In C++11 and C++14, we were able to use this
math.h library in C++ applications. After the C++17 standard, this library is modernized in the
cmath library, and functions are declared in
<cmath> header for compatibility reasons in modern C++, and the
<math.h> is an optional header to support legacy code. In this post, we list most of these mathematical functions declared in the
<cmath> header of modern C++.
Table of Contents
What is the cmath mathematical functions library in C++?
The CMath Mathematical Special Functions Header
<cmath> defines mathematical functions and symbols in the std namespace, and previous math functions are also included. It may also define them in the global namespace. You have to add a std namespace using
namespace std; or you should use the
std:: prefix for each math function.
Some of the mathematical special functions are added to the C++17 cmath library header by the contents of the former international standard ISO/IEC 29124:2010 Math.h functions added too. These are only available in namespace std. If you do not use namespace you should add
std:: prefix to use these modern math functions.
In general, they are mostly double functions and can be slower but they have more accurate results. In the example
sin() is used with
sinf() used with
float variables (same as C++11, faster, less accurate), and
sinl() used with
long double variables (same as C++11, slower, more accurate).
Here is a simple C++ example using the
double d = std::sin(1.0); // double
float f = std::sinf(1.0); // float (C++11)
long double l = std::sinl(1.0); // long double (C++11)
What Are The CMath Mathematical Functions in Modern C++?
Here are some of most used mathematical functions defined in
Basic Math Functions
Here are basic functions,
|fabsf / abs
|signed remainder as well as the three last bits of the division operation
|maximum value of two parameters
|minimum value of two parameters
|positive difference of two parameters
Here are exponential functions,
|power of e
|power of 2
|power of e minus one
|ln x, logarithm (base e)
|logarithm (base 10)
|logarithm (base 2)
|ln( 1 + x ) , natural logarithm (base e)
Here are power functions.
|x power y
|square root x
|cubic root x
|hypotenuse of x, y or x, y, z
Here are trigonometric functions.
|arcs sine x
|arc cosine x
|arc tangent x
|arc tangent of x and y
Hyperbolic Trigonometric Functions
Here are hyperbolic trigonometric functions,\.
|hyperbolic sine x
|hyperbolic cosine x
|hyperbolic tangent x
|hyperbolic arcs sine x
|hyperbolic arc cosine x
|hyperbolic arc tangent x
Here are nearest functions.
|nearest integer not less than x
|nearest integer not greater than x
|nearest integer not greater in magnitude than x
|nearest integer, rounding away from zero in halfway cases
|nearest integer using current rounding mode
|nearest integer using current rounding mode with
exception if the result differs
Note that, by the C++20 standard, only default names of math functions are used. For example,
sin() is used for the
long double versions.
Other Modern Functions in C++
There are many other functions and new modern mathematical functions in the C++17
cmath header. Such as, functions for associated Laguerre polynomials, The elliptic integral of the first kind functions, Cylindrical Bessel functions (of the first kind), Cylindrical Neumann functions, Exponential integral functions, Hermite polynomials functions, Legendre polynomials functions, Laguerre polynomials, Riemann zeta function, and some spherical functions of them.
For more details about changes in C++17 standard, please see this https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0226r1.pdf
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