@stdlib/math-base-tools-evalpoly-compile-c

evalpoly

Compile a C function for evaluating a polynomial.

Installation

npm install @stdlib/math-base-tools-evalpoly-compile-c

Usage

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

compile( c[, options] )

Compiles a C function for evaluating 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., double or float). Default: 'double'.
• name: function name. Default: 'evalpoly'.

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

/**
* 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
*
* @param x   value at which to evaluate the polynomial
* @return    evaluated polynomial
*/
static double evalpoly( const double x ) {
    return 3.0 + (x * (2.0 + (x * 1.0)));
}

To generate a function having a custom name and supporting single-precision floating-point numbers, provide the corresponding options.

var opts = {
    'dtype': 'float',
    'name': 'polyval123'
};
var str = compile( [ 3.0, 2.0, 1.0 ], opts );
// returns <string>

For the previous example, the output string would correspond to the following function:

/**
* 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
*
* @param x   value at which to evaluate the polynomial
* @return    evaluated polynomial
*/
static float polyval123( const float x ) {
    return 3.0f + (x * (2.0f + (x * 1.0f)));
}

Notes

• The coefficients should be ordered in ascending degree, thus matching summation notation.
• The function is intended for non-browser environments for the purpose of generating functions for inclusion in source 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-c' );

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 function for evaluating a polynomial:
str = compile( coef );
console.log( str );

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2023. The Stdlib Authors.