cosm1

Compute cos(x) - 1.

Usage

var cosm1 = require( '@stdlib/math/base/special/cosm1' );

cosm1( x )

Computes cos(x) - 1, where cos is the cosine of a number (in radians). This function should be used instead of manually calculating cos(x) - 1 when the argument is near unity.

var PI = require( '@stdlib/constants/float64/pi' );

var v = cosm1( 0.0 );
// returns 0.0

v = cosm1( PI/4.0 );
// returns ~-0.293

v = cosm1( -PI/6.0 );
// returns ~-0.134

v = cosm1( NaN );
// returns NaN

Examples

var linspace = require( '@stdlib/array/base/linspace' );
var PI = require( '@stdlib/constants/float64/pi' );
var cosm1 = require( '@stdlib/math/base/special/cosm1' );

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

var i;
for ( i = 0; i < x.length; i++ ) {
    console.log( cosm1( x[ i ] ) );
}