@stdlib/math-base-special-cospi NPM

cospi

$NPM version$ $Build Status$ $Coverage Status$

Compute the cosine of a number times π.

Installation

npm install @stdlib/math-base-special-cospi

Usage

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

cospi( x )

Computes cos(πx) more accurately than cos(pi*x), especially for large x.

var y = cospi( 0.0 );
// returns 1.0

y = cospi( 0.5 );
// returns 0.0

y = cospi( 0.1 );
// returns ~0.951

y = cospi( NaN );
// returns NaN

Examples

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

var x = linspace( -100.0, 100.0, 100 );

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

C APIs

Usage

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

stdlib_base_cospi( x )

Computes cos(πx) more accurately than cos(pi*x), especially for large x.

double out = stdlib_base_cospi( 0.5 );
// returns 0.0

The function accepts the following arguments:

x: [in] double input value.

double stdlib_base_cospi( const double x );

Examples

#include "stdlib/math/base/special/cospi.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_cospi( x[ i ] );
        printf( "cospi(%lf) = %lf\n", x[ i ], y );
    }
}

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.