Haversine

Compute the half-value versed sine.

The half-value versed sine is defined as

h a v e r s i n left-parenthesis theta right-parenthesis equals StartFraction 1 plus cosine theta Over 2 EndFraction

Usage

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

haversin( x )

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

var v = haversin( 0.0 );
// returns 0.0

v = haversin( Math.PI/2.0 );
// returns ~0.5

v = haversin( -Math.PI/6.0 );
// returns ~0.06699

Examples

var linspace = require( '@stdlib/math/utils/linspace' );
var haversin = require( '@stdlib/math/base/special/haversin' );

var x = linspace( 0.0, 2.0*Math.PI, 100 );
var i;

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