Computes the dot product between two numeric arrays.
npm install compute-dotDot Product
===
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> Computes the dot product between two arrays.
`` bash`
$ npm install compute-dot
For use in the browser, use browserify.
` javascript`
var dot = require( 'compute-dot' );
#### dot( x, y[, accessor] )
Computes the dot product between two arrays of equal length.
` javascript`
var val = dot( [1,2,3], [4,5,6] );
// returns 32
To compute the dot product between nested array values, provide an accessor function for accessing numeric values.
` javascript
var x = [
{'x':2},
{'x':4},
{'x':5}
];
var y = [
[1,3],
[2,1],
[3,5]
];
function getValue( d, i, j ) {
if ( j === 0 ) {
return d.x;
}
return d[ 1 ];
}
var val = dot( x, y, getValue );
// returns 35
`
The accessor function is provided three arguments:
- __d__: current datum.
- __i__: current datum index.
- __j__: array index; e.g., array x has index 0 and array y has index 1.
If provided empty arrays, the function returns null.
` javascript
var dot = require( 'compute-dot' );
// Simulate some data...
var x = new Array( 100 ),
y = new Array( 100 );
var val;
for ( var i = 0; i < x.length; i++ ) {
val = Math.round( Math.random()*100 ) + 1;
x[ i ] = val;
if ( i % 2 === 0 ) {
val = -val;
}
y[ i ] = 1 / val;
}
console.log( dot( x, y ) );
// returns ~0 (floating-point errors)
`
To run the example code from the top-level application directory,
` bash`
$ node ./examples/index.js
Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
` bash`
$ make test
All new feature development should have corresponding unit tests to validate correct functionality.
This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
` bash`
$ make test-cov
Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,
` bash``
$ make view-cov
---
Copyright © 2014-2015. Athan Reines.
[npm-image]: http://img.shields.io/npm/v/compute-dot.svg
[npm-url]: https://npmjs.org/package/compute-dot
[travis-image]: http://img.shields.io/travis/compute-io/dot/master.svg
[travis-url]: https://travis-ci.org/compute-io/dot
[coveralls-image]: https://img.shields.io/coveralls/compute-io/dot/master.svg
[coveralls-url]: https://coveralls.io/r/compute-io/dot?branch=master
[dependencies-image]: http://img.shields.io/david/compute-io/dot.svg
[dependencies-url]: https://david-dm.org/compute-io/dot
[dev-dependencies-image]: http://img.shields.io/david/dev/compute-io/dot.svg
[dev-dependencies-url]: https://david-dm.org/dev/compute-io/dot
[github-issues-image]: http://img.shields.io/github/issues/compute-io/dot.svg
[github-issues-url]: https://github.com/compute-io/dot/issues