evalpoly

Usage

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

compile( c[, options] )

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>

The function supports the following options:

• dtype: input argument floating-point data type (e.g., float64 or float32). Default: 'float64'.

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)));
}


// EXPORTS //

module.exports = evalpoly;

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

By default, the function assumes double-precision floating-point arithmetic. To emulate single-precision floating-point arithmetic, set the dtype option to 'float32'.

var str = compile( [ 3.0, 2.0, 1.0 ], {
    'dtype': 'float32'
});
// returns <string>

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

'use strict';

// MODULES //

var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );


// 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 float64ToFloat32(3.0 + float64ToFloat32(x * float64ToFloat32(2.0 + float64ToFloat32(x * 1.0)))); // eslint-disable-line max-len
}


// EXPORTS //

module.exports = evalpoly;