<math.h> provides standard math functions: trigonometric, exponential, logarithmic, rounding, and IEEE 754 utilities (isnan, isinf). Append f for float or l for long double versions.

Compile with -lm to link the math library.

This example demonstrates basic math functions and special-value checking.

// compile: gcc -o mathexample mathexample.c -lm
// run: ./mathexample
// description: math functions and special value detection
 
#include <math.h>
#include <stdio.h>
 
int main() {
    printf("sqrt(2) = %.6f\n", sqrt(2.0));
    printf("sin(pi/4) = %.6f\n", sin(M_PI / 4));
    printf("exp(1) = %.6f\n", exp(1.0));
    printf("log(10) = %.6f\n", log(10.0));
 
    double nan_val = 0.0 / 0.0;
    double inf_val = 1.0 / 0.0;
    printf("isnan(nan): %d, isinf(inf): %d\n", isnan(nan_val), isinf(inf_val));
 
    return 0;
}