C Programming by EezyTutorials

C - Math Functions

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C provides a set of standard math functions in the math.h library for performing common mathematical operations like square root, power, trigonometry, and more.

Common Math Functions

  • abs(x) - Absolute value (int)
  • fabs(x) - Absolute value (float/double)
  • ceil(x) - Smallest integer not less than x
  • floor(x) - Largest integer not greater than x
  • sqrt(x) - Square root
  • cbrt(x) - Cube root
  • pow(x, y) - x raised to the power y
  • exp(x) - Exponential function e^x
  • log(x) - Natural logarithm (base e)
  • log10(x) - Logarithm base 10
  • sin(x) - Sine (x in radians)
  • cos(x) - Cosine (x in radians)
  • tan(x) - Tangent (x in radians)
  • asin(x) - Arc sine (result in radians)
  • acos(x) - Arc cosine (result in radians)
  • atan(x) - Arc tangent (result in radians)
  • sinh(x) - Hyperbolic sine
  • cosh(x) - Hyperbolic cosine
  • tanh(x) - Hyperbolic tangent
  • fmod(x, y) - Floating-point remainder of x/y
  • modf(x, &intpart) - Splits x into integer and fractional parts
  • frexp(x, &exp) - Breaks x into normalized fraction and exponent
  • ldexp(x, exp) - Multiplies x by 2 raised to exp
  • hypot(x, y) - Square root of (x*x + y*y)
  • round(x) - Rounds x to nearest integer
  • trunc(x) - Truncates x to integer

Example

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

int main() {
    printf("abs(-5) = %d\\n", abs(-5));
    printf("fabs(-5.5) = %.2f\\n", fabs(-5.5));
    printf("ceil(2.3) = %.2f\\n", ceil(2.3));
    printf("floor(2.7) = %.2f\\n", floor(2.7));
    printf("sqrt(16) = %.2f\\n", sqrt(16));
    printf("cbrt(27) = %.2f\\n", cbrt(27));
    printf("pow(2, 3) = %.2f\\n", pow(2, 3));
    printf("exp(1) = %.2f\\n", exp(1));
    printf("log(2.71828) = %.2f\\n", log(2.71828));
    printf("log10(100) = %.2f\\n", log10(100));
    printf("sin(0) = %.2f\\n", sin(0));
    printf("cos(0) = %.2f\\n", cos(0));
    printf("tan(0) = %.2f\\n", tan(0));
    printf("asin(1) = %.2f\\n", asin(1));
    printf("acos(1) = %.2f\\n", acos(1));
    printf("atan(1) = %.2f\\n", atan(1));
    printf("sinh(0) = %.2f\\n", sinh(0));
    printf("cosh(0) = %.2f\\n", cosh(0));
    printf("tanh(0) = %.2f\\n", tanh(0));
    printf("fmod(5.3, 2) = %.2f\\n", fmod(5.3, 2));
    double intpart, fracpart;
    fracpart = modf(3.14, &intpart);
    printf("modf(3.14): intpart = %.2f, fracpart = %.2f\\n", intpart, fracpart);
    int exp;
    double frac = frexp(8.0, &exp);
    printf("frexp(8.0): frac = %.2f, exp = %d\\n", frac, exp);
    printf("ldexp(0.5, 4) = %.2f\\n", ldexp(0.5, 4));
    printf("hypot(3, 4) = %.2f\\n", hypot(3, 4));
    printf("round(2.5) = %.2f\\n", round(2.5));
    printf("trunc(2.9) = %.2f\\n", trunc(2.9));
    return 0;
}

Output (partial):

abs(-5) = 5
fabs(-5.5) = 5.50
ceil(2.3) = 3.00
floor(2.7) = 2.00
sqrt(16) = 4.00
cbrt(27) = 3.00
pow(2, 3) = 8.00
exp(1) = 2.72
log(2.71828) = 1.00
log10(100) = 2.00
sin(0) = 0.00
cos(0) = 1.00
tan(0) = 0.00
asin(1) = 1.57
acos(1) = 0.00
atan(1) = 0.79
sinh(0) = 0.00
cosh(0) = 1.00
tanh(0) = 0.00
fmod(5.3, 2) = 1.30
modf(3.14): intpart = 3.00, fracpart = 0.14
frexp(8.0): frac = 0.50, exp = 4
ldexp(0.5, 4) = 8.00
hypot(3, 4) = 5.00
round(2.5) = 3.00
trunc(2.9) = 2.00

Compile tip

On many systems you must link with the math library: gcc prog.c -o prog -lm.

Summary

Use math.h for advanced mathematical operations in C. Prefer double for precision, and be mindful of floating-point rounding.