ddot

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

The dot product (or scalar product) is defined as

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 );