C library - cimag() function

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The C complex library cimag() function is typically used to extract the imaginary part of the complex number. A complex number is composed by two components: a real and an imaginary (imag) parts.

If the imag (imaginary) part is of the "float" type, we can use cimagf() to get imag part, and For long double, use cimagl().

Syntax

Following is the C library syntax of cimag() function −

double cimag( double complex z )

Parameters

This function accepts a single parameter −

• Z − It represent a complex number.

Return Value

This function returns the imag(imaginary) part of the complex number(z).

Example 1

Following is the basic c program to demonstrate the use of cimag() to obtain the imaginary part of the complex number(z).

#include <stdio.h>
#include <complex.h>
int main(void){
   double complex z = 1.0 + 2.0 * I;
   printf("The imag part of z: %.1fi\n", cimag(z));
}

Output

Following is the output −

The imag part of z: 2.0i

Example 2

Let's see another example, we use the cimag() function to obtain the imaginary part of the generated complex number.

#include <stdio.h>
#include <complex.h>

int main() {
   double real = 5.0;
   double imag = 6.0;

   // Use the CMPLX function to create complex number
   double complex z = CMPLX(real, imag);

   printf("The complex number is: %.2f + %.2fi\n", creal(z), cimag(z));

   // obtain the image part
   // use cimag()
   printf("The imaginary part of z: %.1fi\n", cimag(z));

   return 0;
}

Output

Following is the output −

The complex number is: 5.00 + 6.00i
The imaginary part of z: 6.0i

Example 3

The below example use the cimag() function to extract the imaginary part after the addition of the two complex number (z).

#include <stdio.h>
#include <complex.h>

int main() {
   double real1 = 2.0, imag1 = 3.0;
   double real2 = 4.0, imag2 = 5.0;
   
   // Use the CMPLX function 
   double complex z1 = CMPLX(real1, imag1);
   double complex z2 = CMPLX(real2, imag2);
   // add two complex number
   double complex sum = z1 + z2;
   
   // Display the results of the operations
   printf("Resultant z: %.2f + %.2fi\n", creal(sum), cimag(sum));
   printf("Imaginary part of resultant z: %.2fi\n", cimag(sum));
   
   return 0;
}

Output

Following is the output −

Resultant z: 6.00 + 8.00i
Imaginary part of resultant z: 8.00i