_Complex_I
From cppreference.com
C
Concurrency support (C11)
Complex number arithmetic
Types and the imaginary constant
Manipulation
Power and exponential functions
Trigonometric functions
Hyperbolic functions
Defined in header
<complex.h>
#define _Complex_I /* unspecified */
(since C99)
The _Complex_I macro expands to a value of type const float _Complex with the value of the imaginary unit.
Contents
[edit] Notes
This macro may be used when I is not available, such as when it has been undefined by the application.
Unlike _Imaginary_I and CMPLX , use of this macro to construct a complex number may lose the sign of zero on the imaginary part.
[edit] Example
Run this code
#include <stdio.h> #include <complex.h> #undef I #define J _Complex_I // can be used to redefine I int main(void) { // can be used to construct a complex number double complex z = 1.0 + 2.0 * _Complex_I; printf ("1.0 + 2.0 * _Complex_I = %.1f%+.1fi\n", creal (z), cimag (z)); // sign of zero may not be preserved double complex z2 = 0.0 + -0.0 * _Complex_I; printf ("0.0 + -0.0 * _Complex_I = %.1f%+.1fi\n", creal (z2), cimag (z2)); }
Possible output:
1.0 + 2.0 * _Complex_I = 1.0+2.0i 0.0 + -0.0 * _Complex_I = 0.0+0.0i
[edit] References
- C23 standard (ISO/IEC 9899:2024):
- 7.3.1/4 _Complex_I (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.3.1/4 _Complex_I (p: 136)
- C11 standard (ISO/IEC 9899:2011):
- 7.3.1/4 _Complex_I (p: 188)
- C99 standard (ISO/IEC 9899:1999):
- 7.3.1/2 _Complex_I (p: 170)