@stdlib/blas-ddot NPM

ddot

Calculate the dot product of two double-precision floating-point vectors.

The dot product (or scalar product) is defined as

Installation

npm install @stdlib/blas-ddot

Usage

var ddot = require( '@stdlib/blas-ddot' );

ddot( x, y )

Calculates the dot product of two double-precision floating-point vectors x and y.

var Float64Array = require( '@stdlib/array-float64' );
var array = require( '@stdlib/ndarray-array' );

var x = array( new Float64Array( [ 4.0, 2.0, -3.0, 5.0, -1.0 ] ) );
var y = array( new Float64Array( [ 2.0, 6.0, -1.0, -4.0, 8.0 ] ) );

var z = ddot( x, y );
// returns -5.0

The function has the following parameters:

x: a 1-dimensional ndarray whose underlying data type is float64.
y: a 1-dimensional ndarray whose underlying data type is float64.

If provided empty vectors, the function returns 0.0.

var Float64Array = require( '@stdlib/array-float64' );
var array = require( '@stdlib/ndarray-array' );

var x = array( new Float64Array() );
var y = array( new Float64Array() );

var z = ddot( x, y );
// returns 0.0

Notes

ddot() provides a higher-level interface to the BLAS level 1 function ddot.

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var Float64Array = require( '@stdlib/array-float64' );
var array = require( '@stdlib/ndarray-array' );
var ddot = require( '@stdlib/blas-ddot' );

var x = array( new Float64Array( 10 ) );
var y = array( new Float64Array( 10 ) );

var rand1 = discreteUniform.factory( 0, 100 );
var rand2 = discreteUniform.factory( 0, 10 );

var i;
for ( i = 0; i < x.length; i++ ) {
    x.set( i, rand1() );
    y.set( i, rand2() );
}
console.log( x.toString() );
console.log( y.toString() );

var z = ddot( x, y );
console.log( z );

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.