math.h library

To help us solve mathematical functions, we can use a variety of libraries, depending on our goals. The main library is math.h (https://cppreference.com/w/c/header/math.html).

If we also want to include math with complex numbers, we can use complex.h and/or tgmath.h libraries.

/**
 * File:        math.c
 * Author:      Risto Heinsar
 * Created:     05.10.2015
 * Modified:    26.09.2021
 *
 * Description: Some example use of math.h library. 
 * 
 * Note:        To use math.h library You must compile the program with the
 *              linker flag "-lm", without quotes. In geany, you can add the -lm
 *              to build path under build -> set build commands.
 */

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

int main(void)
{
    // Integer division leads to integer answers with decimal places truncated
    printf("5 / 10 is %d\n", 5 / 10);
    printf("10 / 10 is %d\n", 10 / 10);
    printf("28 / 10 is %d\n\n", 28 / 10);
    
    // To get deimal places, at least one operand has to be float/double
    printf("9.0 / 10 is %.2f\n", 9.0 / 10);
    printf("9 / 10.0 is %.2f\n", 9 / 10.0);
    printf("Using typecasting: 9 / 10 is %.2f\n\n", 9 / (float)10);

    float num1 = 9;
    float num2 = -5.4f;
    float num3 = pow(num1, 2);
    
    // Using math.h functions
    printf("Num1 squared is %.2f\n", pow(num1, 2));
    printf("Num1 squared can be also found like this: %.2f\n", num3);
    printf("Number 7 to the power of 3 is: %.2f\n", pow(7, 3));
    printf("The square root of num1 is: %.2f\n", sqrt(num1));
    printf("Alternative square root: %.2f\n", pow(num1, 1.0/2.0));
    
    float equation = num1 * pow(num2, 2) + sqrt(num1);
    printf("The solution for the equation %.3f\n", equation);
    
    return 0;
}

/**

* File: math.c

* Author: Risto Heinsar

* Created: 05.10.2015

* Modified: 26.09.2021

* Description: Some example use of math.h library.

* Note: To use math.h library You must compile the program with the

* linker flag "-lm", without quotes. In geany, you can add the -lm

* to build path under build -> set build commands.

#include <stdio.h>

#include <math.h>

int main(void)

{

// Integer division leads to integer answers with decimal places truncated

printf("5 / 10 is %d\n", 5 / 10);

printf("10 / 10 is %d\n", 10 / 10);

printf("28 / 10 is %d\n\n", 28 / 10);

// To get deimal places, at least one operand has to be float/double

printf("9.0 / 10 is %.2f\n", 9.0 / 10);

printf("9 / 10.0 is %.2f\n", 9 / 10.0);

printf("Using typecasting: 9 / 10 is %.2f\n\n", 9 / (float)10);

float num1 = 9;

float num2 = -5.4f;

float num3 = pow(num1, 2);

// Using math.h functions

printf("Num1 squared is %.2f\n", pow(num1, 2));

printf("Num1 squared can be also found like this: %.2f\n", num3);

printf("Number 7 to the power of 3 is: %.2f\n", pow(7, 3));

printf("The square root of num1 is: %.2f\n", sqrt(num1));

printf("Alternative square root: %.2f\n", pow(num1, 1.0/2.0));

float equation = num1 * pow(num2, 2) + sqrt(num1);

printf("The solution for the equation %.3f\n", equation);

return 0;

}

Notice the following

When compiling the program, we must specify an additional build argument (-lm) to the compiler. This links the mathematics library to our program.
Math functions typically return their result. If you want to use the result later on, you need to store the result in a variable. If however you only need it as a part of a larger equation, you can use it in-place without separately storing the result.
To get n-th root, we can use the properties of power. Make sure to use floats for the division (e.g. 1.0 instead of 1). This is necessary due to integer division truncating the decimal places.