Math Functions in C

The C standard library provides mathematical functions for rounding, powers, roots, logarithms, trigonometry and floating-point calculations. Most are declared in <math.h>; abs() for integers is declared in <stdlib.h>.

Common C Math Functions Top ↑

Small Math Example Top ↑

#include <math.h>
#include <stdio.h>

int main(void) {
    double value = 5.7;

    printf("floor: %.1f\n", floor(value));
    printf("ceil : %.1f\n", ceil(value));
    printf("sqrt : %.3f\n", sqrt(value));

    return 0;
}

Output

floor: 5.0
ceil : 6.0
sqrt : 2.387

Choose the Right Function Top ↑

• Use abs() for an integer absolute value.
• Use floor(), ceil(), round() or trunc() depending on the exact rounding rule required.
• Use fmod() for floating-point remainders; the % operator is for integer operands.
• Trigonometric functions use radians, not degrees.
• Check domain restrictions for functions such as sqrt() and log().

Subhendu Mohapatra

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