7. Math Functions

Math Prototype in C

To perform complex mathematical operations in C, we include the <math.h> header file. It provides a wide collection of built-in mathematical functions.

Note: In Linux/GCC, you often need to compile programs using math.h with the -lm flag (e.g., gcc program.c -lm).

Function Prototypes in <math.h>

Most functions in <math.h> take double arguments and return a double value.

Here are the most commonly used math functions:

1. Power and Root Functions

• double pow(double base, double exponent);: Returns the base raised to the power of exponent.
• double sqrt(double x);: Returns the square root of x. (x must be non-negative).
• double cbrt(double x);: Returns the cube root of x.

2. Rounding Functions

• double ceil(double x);: Rounds UP to the nearest integer. (e.g., ceil(3.2) becomes 4.0).
• double floor(double x);: Rounds DOWN to the nearest integer. (e.g., floor(3.8) becomes 3.0).
• double round(double x);: Rounds to the absolute nearest integer (normal rounding).

3. Absolute Value Functions

• int abs(int x);: Found in <stdlib.h>. Returns the absolute value of an integer.
• double fabs(double x);: Found in <math.h>. Returns the absolute value of a floating-point number.

4. Trigonometric Functions

(Note: Angles passed to these functions must be in Radians, not Degrees)

• double sin(double x);: Returns the sine of an angle.
• double cos(double x);: Returns the cosine of an angle.
• double tan(double x);: Returns the tangent of an angle.

5. Logarithmic and Exponential Functions

• double exp(double x);: Returns e raised to the power of x.
• double log(double x);: Returns the natural logarithm (base e) of x.
• double log10(double x);: Returns the common logarithm (base 10) of x.

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Example Program

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

int main() {
    double x = 9.0;
    double pt_val = 3.6;

    printf("Square root of %.2f is %.2f\n", x, sqrt(x)); // 3.00
    printf("3 raised to power 4 is %.2f\n", pow(3, 4)); // 81.00
    printf("Ceil of %.2f is %.2f\n", pt_val, ceil(pt_val));   // 4.00
    printf("Floor of %.2f is %.2f\n", pt_val, floor(pt_val)); // 3.00
    printf("Absolute value of -10.5 is %.2f\n", fabs(-10.5)); // 10.50

    return 0;
}