/C

# conjf, conj, conjl

Defined in header `<complex.h>`
`float complex       conjf( float complex z );`
(1) (since C99)
`double complex      conj( double complex z );`
(2) (since C99)
`long double complex conjl( long double complex z );`
(3) (since C99)
Defined in header `<tgmath.h>`
`#define conj( z )`
(4) (since C99)
1-3) Computes the complex conjugate of `z` by reversing the sign of the imaginary part.
4) Type-generic macro: if `z` has type `long double complex`, `long double imaginary`, or `long double`, `conjl` is called. If `z` has type `float complex`, `float imaginary`, or `float`, `conjf` is called. If `z` has type `double complex`, `double imaginary`, `double`, or any integer type, `conj` is called.

### Parameters

 z - complex argument

### Return value

The complex conjugate of `z`.

### Notes

On C99 implementations that do not implement `I` as `_Imaginary_I`, `conj` may be used to obtain complex numbers with negative zero imaginary part. In C11, the macro `CMPLX` is used for that purpose.

### Example

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

int main(void)
{
double complex z = 1.0 + 2.0*I;
double complex z2 = conj(z);
printf("The conjugate of %.1f%+.1fi is %.1f%+.1fi\n",
creal(z), cimag(z), creal(z2), cimag(z2));

printf("Their product is %.1f%+.1fi\n", creal(z*z2), cimag(z*z2));
}```

Output:

```The conjugate of 1.0+2.0i is 1.0-2.0i
Their product is 5.0+0.0i```

### References

• C11 standard (ISO/IEC 9899:2011):
• 7.3.9.4 The conj functions (p: 198)
• 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):
• 7.3.9.3 The conj functions (p: 179)
• 7.22 Type-generic math <tgmath.h> (p: 335-337)
• G.7 Type-generic math <tgmath.h> (p: 480)

 C++ documentation for `conj`