cimagf, cimag, cimagl

Defined in header <complex.h>
float       cimagf( float complex z );
(1) (since C99)
double      cimag( double complex z );
(2) (since C99)
long double cimagl( long double complex z );
(3) (since C99)
Defined in header <tgmath.h>
#define cimag( z )
(4) (since C99)
1-3) Returns the imaginary part of z.
4) Type-generic macro: if z has type long double complex, long double imaginary, or long double, cimagl is called. If z has type float complex, float imaginary, or float, cimagf is called. If z has type double complex, double imaginary, double, or any integer type, cimag is called.


z - complex argument

Return value

The imaginary part of z.

This function is fully specified for all possible inputs and is not subject to any errors described in math_errhandling.


For any complex variable z, z == creal(z) + I*cimag(z).


#include <stdio.h>
#include <complex.h>
int main(void)
    double complex z = 1.0 + 2.0*I;
    printf("%f%+fi\n", creal(z), cimag(z));




  • C11 standard (ISO/IEC 9899:2011):
    • The cimag functions (p: 197)
    • 7.25 Type-generic math <tgmath.h> (p: 373-375)
    • G.7 Type-generic math <tgmath.h> (p: 545)
  • C99 standard (ISO/IEC 9899:1999):
    • The cimag functions (p: 178-179)
    • 7.22 Type-generic math <tgmath.h> (p: 335-337)
    • G.7 Type-generic math <tgmath.h> (p: 480)

See also

computes the real part of a complex number
C++ documentation for imag

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