C <math.h>

C Math Functions: The <math.h> Library

The <math.h> header file in C provides a wide range of powerful mathematical functions to perform complex calculations. Whether you need to calculate square roots, exponentiation, logarithms, or trigonometric values, the math library has built-in solutions.

By default, most functions in <math.h> accept and return values of type double for high-precision calculations.

1. Exponents and Roots

• sqrt(double x): Calculates the square root of x.
• pow(double base, double exp): Calculates base raised to the power of exp.

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

int main() {
    double num = 16.0;
    printf("Square root of 16 is: %f\n", sqrt(num));
    printf("2 to the power of 3 is: %f\n", pow(2.0, 3.0));
    return 0;
}

2. Rounding Functions

If you have a floating-point number and need to convert it to a whole number representation, <math.h> provides several rounding options:

• ceil(double x): Rounds the number up to the nearest integer.
• floor(double x): Rounds the number down to the nearest integer.
• round(double x): Rounds to the mathematically nearest integer (e.g., 2.5 becomes 3.0).

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

int main() {
    double val = 4.3;
    printf("Original: %f\n", val);
    printf("Ceil (Up): %f\n", ceil(val));   // Output: 5.000000
    printf("Floor (Down): %f\n", floor(val)); // Output: 4.000000
    printf("Round: %f\n", round(val));      // Output: 4.000000
    return 0;
}

3. Absolute Values

To get the positive version of a number (distance from zero), use absolute value functions:

• fabs(double x): Returns the absolute value of a floating-point number (part of <math.h>).
• abs(int x): Returns the absolute value of an integer (Note: This function is actually located in <stdlib.h>).

4. Trigonometric Functions

C provides standard trigonometric functions like sin(), cos(), and tan().

Important: These functions expect their arguments to be provided in radians, not degrees!

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

#define PI 3.14159265
int main() {
    double degrees = 90.0;
    double radians = degrees * (PI / 180.0); // Convert degrees to radians
    printf("The sine of 90 degrees is: %f\n", sin(radians)); // Output: ~1.000000
    return 0;
}