acos

Compute the arccosine of a double-precision floating-point number.

Usage

var acos = require( '@stdlib/math/base/special/acos' );

acos( x )

Computes the arccosine of a double-precision floating-point number (in radians).

var v = acos( 1.0 );
// returns 0.0

v = acos( 0.707 ); // ~pi/4
// returns ~0.7855

v = acos( 0.866 ); // ~pi/6
// returns ~0.5236

v = acos( NaN );
// returns NaN

The domain of x is restricted to [-1,1]. If |x| > 1, the function returns NaN.

var v = acos( -3.14 );
// returns NaN

Examples

var linspace = require( '@stdlib/array/base/linspace' );
var acos = require( '@stdlib/math/base/special/acos' );

var x = linspace( -1.0, 1.0, 100 );

var i;
for ( i = 0; i < x.length; i++ ) {
    console.log( acos( x[ i ] ) );
}

C APIs

Usage

#include "stdlib/math/base/special/acos.h"

stdlib_base_acos( x )

Computes the arccosine of a double-precision floating-point number (in radians).

double out = stdlib_base_acos( 1.0 );
// returns 0.0

out = stdlib_base_acos( 0.707 ); // ~pi/4
// returns ~0.7855

The function accepts the following arguments:

x: [in] double input value (in radians).

double stdlib_base_acos( const double x );

Examples

#include "stdlib/math/base/special/acos.h"
#include <stdio.h>

int main( void ) {
    const double x[] = { -1.0, -0.78, -0.56, -0.33, -0.11, 0.11, 0.33, 0.56, 0.78, 1.0 };
    
    double v;
    int i;
    for ( i = 0; i < 10; i++ ) {
        v = stdlib_base_acos( x[ i ] );
        printf( "acos(%lf) = %lf\n", x[ i ], v );
    }
}