# cacosf, cacos, cacosl

< c‎ | numeric‎ | complex

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Complex number arithmetic
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 cacos casin catan
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 Defined in header `` float complex       cacosf( float complex z ); (since C99) double complex      cacos( double complex z ); (since C99) long double complex cacosl( long double complex z ); (since C99)

Computes the complex arc cosine of `z` with branch cuts outside the interval [−1,+1] along the real axis.

## Contents

### Parameters

 z - complex argument

### Return value

The complex arc cosine of `z` in the interval [0; π] along the real axis and in the interval (−∞; ∞) along the imaginary axis.

### Example

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

int main()
{
double complex z;

z = ccos(1.0+2.0*I);
printf("ccos(1.0+2.0i)            ==> %f%+fi\n", creal(z),cimag(z));

z = cacos(2.032723-3.051898*I);
printf("cacos(2.032723-3.051898i) ==> %f%+fi\n", creal(z),cimag(z));

return 0;
}```

Output:

```ccos(1.0+2.0i)            ==> 2.032723-3.051898i
cacos(2.032723-3.051898i) ==> 1.000000+2.000000i```