ndarray-function-basis

ndarray-function-basis

Construct an basis ndarray given a list of values and functions

Introduction

This module extends the Vandermonde matrix to a list of numbers or functions. It constructs a set of basis vectors that can be used in a least squares curve fit. It's little more than a thin convenience wrapper around ndarray-fill.

Usage

require([dest, ]x, inputs)

• dest: a destination array. If not provided, an ndarray of type 'array' will be created. If provided, the first dimension must match the length of x, and the second must match the length of inputs.
• x: a ndarray of numbers at which the inputs are evaluated
• inputs: an Array of either Functions or Numbers. If a Function, it is evaluated at x; if a Number, x is ignored for this input.

Example

For example, to construct a sinusoidal basis with period 2 * π and a constant offset,

var basis = require('ndarray-function-basis');
var ndarray = require('ndarray');

basis(ndarray([1, 2, 3, 4]), [1, Math.sin, Math.cos]);
// => 
//  1.000    0.841    0.540
//  1.000    0.909   -0.416
//  1.000    0.141   -0.990
//  1.000   -0.757   -0.654

See also:

• ndarray-householder-qr: Householder QR for least squares curve-fitting
• ndarray-vandermonde: Construct a Vandermonde (polynomial) basis

Credits

(c) 2015 Ricky Reusser. MIT License