evalpoly

Compile a module for evaluating a polynomial.

Usage

var compile = require( '@stdlib/math/base/tools/evalpoly-compile' );

compile( c )

Compiles a module string containing an exported function which evaluates a polynomial having coefficients c.

var str = compile( [ 3.0, 2.0, 1.0 ] );
// returns <string>

In the example above, the output string would correspond to the following module:

'use strict';

// MAIN //

/**
* Evaluates a polynomial.
*
* ## Notes
*
* -   The implementation uses [Horner's rule][horners-method] for efficient computation.
*
* [horners-method]: https://en.wikipedia.org/wiki/Horner%27s_method
*
*
* @private
* @param {number} x - value at which to evaluate the polynomial
* @returns {number} evaluated polynomial
*/
function evalpoly( x ) {
    if ( x === 0.0 ) {
        return 3.0;
    }
    return 3.0 + (x * (2.0 + (x * 1.0))); // eslint-disable-line max-len
}


// EXPORTS //

module.exports = evalpoly;

The coefficients should be ordered in ascending degree, thus matching summation notation.

Notes

  • The function is intended for non-browser environments for the purpose of generating module files.

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var Float64Array = require( '@stdlib/array/float64' );
var compile = require( '@stdlib/math/base/tools/evalpoly-compile' );

var coef;
var sign;
var str;
var i;

// Create an array of random coefficients...
coef = new Float64Array( 10 );
for ( i = 0; i < coef.length; i++ ) {
    if ( randu() < 0.5 ) {
        sign = -1.0;
    } else {
        sign = 1.0;
    }
    coef[ i ] = sign * round( randu()*100.0 );
}

// Compile a module for evaluating a polynomial:
str = compile( coef );
console.log( str );