C Library math.h (original) (raw)

Last Updated : 23 Jul, 2025

The <math.h> header file in C contains the standard math library functions which can be utilized for various mathematical operations. All math.h library functions accept double type as an argument and return double as a result. It also contains some commonly used constants defined as macros.

**Syntax:

#include <math.h>

After including the header file, we can use its services in the program. There are two types of elements in math.h header file:

• **Functions
• **Macros

math.h Library Functions

These are functions that are defined inside the <math.h> header file that performs a particular mathematical operation when called.

**Example:

C `

// C program to demonstrate the // use of math.h library // functions #include <math.h> #include <stdio.h>

int main() { // two variables for test double x = 3.3, y = 1.1;

// ceil and floor demonstration
printf(
    "Ceil of %.1lf = %.1lf \nFloor of %.1lf = %.1lf\n",
    x, ceil(x), x, floor(x));

// pow function demonstration
printf("%.1lf raised to the power %.1lf = %.1lf\n", x,
       y, pow(x, y));

return 0;

}

`

Output

Ceil of 3.3 = 4.0 Floor of 3.3 = 3.0 3.3 raised to the power 1.1 = 3.7

Commonly used math.h header file functions

math.h Library Macros

They are the macros defined inside <math.h> header file using #define preprocessor. They can be either constant that is replaced by their value when used or either function-like macros.

**Example:

C `

// C program to demonstrate // the use of math.h library // macros #include <math.h> #include <stdio.h>

int main() { // HUGE_VAL macro printf("Value Returned by HUGE_VAL = %.1lf\n", HUGE_VAL);

// isgreater macro demonstration
printf("Value returned by isgreater = %d", isgreater(12.0, 13.0));

return 0;

}

`

Output

Value Returned by HUGE_VAL = inf Value returned by isgreater = 0

**EXAMPLE 2 :

The math.h library in C provides a set of functions for performing mathematical operations. Here are some examples of functions from the math.h library, along with code samples:

1 .double cos(double x): This function returns the cosine of x, where x is an angle in radians.

C `

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

int main(void) { double x = 1.5; double y = 2.0; double z;

z = sin(x);
printf("sin(%.2lf) = %.2lf\n", x, z);
// output: sin(1.50) = 0.99

z = cos(x);
printf("cos(%.2lf) = %.2lf\n", x, z);
// output: cos(1.50) = 0.07

z = tan(x);
printf("tan(%.2lf) = %lf\n", x, z);
// output: tan(1.50) = 14.33

z = asin(x);
printf("asin(%.2lf) = %lf\n", x, z);
// output: asin(1.50) = NAN

z = acos(x);
printf("acos(%.2lf) = %lf\n", x, z);
// output: acos(1.50) = NAN

z = atan(x);
printf("atan(%.2lf) = %lf\n", x, z);
// output: atan(1.50) = 0.98

z = exp(y);
printf("exp(%.2lf) = %lf\n", y, z);
// output: exp(2.00) = 7.39

z = log(y);
printf("log(%.2lf) = %lf\n", y, z);
// output: log(2.00) = 0.69

z = sqrt(y);
printf("sqrt(%.2lf) = %lf\n", y, z);
// output: sqrt(2.00) = 1.41

return 0;

}

`

Output:

sin(1.50) = 0.997495
cos(1.50) = 0.070737
tan(1.50) = 14.101420
asin(1.50) = nan
acos(1.50) = nan
atan(1.50) = 0.982794
exp(2.00) = 7.389056
log(2.00) = 0.693147
sqrt(2.00) = 1.414214

**Note: inf is used to represent positive infinity (very large number that cannot be represented _using double or float.

Here is a list of some commonly used math.h library macros:

**Note: _isgreater(x , y) may look like a function but they are defined as macros in the math.h header file and are replaced by their value in preprocessing.