Havercosine

Compute the half-value versed cosine.

The half-value versed cosine is defined as

$$\mathop{\mathrm{havercos}}(\theta) = \frac{1 + \cos \theta}{2}$$

Usage

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

havercos( x )

Computes the half-value versed cosine (in radians).

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

v = havercos( 3.141592653589793/2.0 );
// returns 0.5

v = havercos( -3.141592653589793/6.0 );
// returns ~0.9330

Examples

var uniform = require( '@stdlib/random/array/uniform' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var TWO_PI = require( '@stdlib/constants/float64/two-pi' );
var havercos = require( '@stdlib/math/base/special/havercos' );

var opts = {
    'dtype': 'float64'
};
var x = uniform( 100, 0.0, TWO_PI, opts );

logEachMap( 'havercos(%0.4f) = %0.4f', x, havercos );

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C APIs

Usage

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

stdlib_base_havercos( x )

Computes the half-value versed cosine (in radians).

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

out = stdlib_base_havercos( 3.141592653589793 / 2.0 );
// returns 0.5

The function accepts the following arguments:

• x: [in] double input value.

double stdlib_base_havercos( const double x );

Examples

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

int main( void ) {
    const double x[] = { 0.0, 0.523, 0.785, 1.047, 3.14 };

    double y;
    int i;
    for ( i = 0; i < 5; i++ ) {
        y = stdlib_base_havercos( x[ i ] );
        printf( "havercos(%lf) = %lf\n", x[ i ], y );
    }
}

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See Also

• @stdlib/math/base/special/haversin: compute the half-value versed sine.
• @stdlib/math/base/special/vercos: compute the versed cosine.