? Math Functions in C

C provides a set of built-in math functions through the math.h header file. These functions handle everything from basic math to trigonometry and logarithms.

? First: Include the Header

c
Function
Description
Example
Result
sqrt(x)
Square root
sqrt(16)
4.0
pow(x, y)
x raised to the power y
pow(2, 3)
8.0
abs(x)
Absolute value (for int)
abs(-5)
5
fabs(x)
Absolute value (for float/double)
fabs(-5.5)
5.5
ceil(x)
Round up to nearest int
ceil(4.2)
5.0
floor(x)
Round down to nearest int
floor(4.9)
4.0
round(x)
Round to nearest int
round(4.5)
5.0
log(x)
Natural log (base e)
log(2.71828)
? 1.0
log10(x)
Log base 10
log10(1000)
3.0
sin(x)
Sine (radians)
sin(M_PI/2)
1.0
cos(x)
Cosine (radians)
cos(0)
1.0
tan(x)
Tangent (radians)
tan(M_PI/4)
1.0
? Example Program
c
#include #include <math.h>int main() {    double x = 9.0;    printf("Square root of %.2f = %.2f\n", x, sqrt(x));    printf("Power of 2^3 = %.2f\n", pow(2, 3));    printf("Ceil of 4.3 = %.2f\n", ceil(4.3));    printf("Floor of 4.7 = %.2f\n", floor(4.7));    printf("Absolute of -10 = %d\n", abs(-10));    return 0;}
?? Notes
Use gcc -lm file.c when compiling — the -lm flag links the math library.
Angles for sin, cos, tan are in radians, not degrees!