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Evaluate a polynomial using double-precision floating-point arithmetic.
A polynomial in a variable x can be expressed as
where c_n, c_{n-1}, ..., c_0 are constants.
import evalpoly from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpoly@esm/index.mjs';You can also import the following named exports from the package:
import { factory } from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpoly@esm/index.mjs';Evaluates a polynomial having coefficients c and degree n at a value x, where n = c.length-1.
var v = evalpoly( [ 3.0, 2.0, 1.0 ], 10 ); // => 3*10^0 + 2*10^1 + 1*10^2
// returns 123.0The coefficients should be ordered in ascending degree, thus matching summation notation.
Uses code generation to in-line coefficients and return a function for evaluating a polynomial using double-precision floating-point arithmetic.
var polyval = evalpoly.factory( [ 3.0, 2.0, 1.0 ] );
var v = polyval( 10.0 ); // => 3*10^0 + 2*10^1 + 1*10^2
// returns 123.0
v = polyval( 5.0 ); // => 3*5^0 + 2*5^1 + 1*5^2
// returns 38.0- For hot code paths in which coefficients are invariant, a compiled function will be more performant than
evalpoly(). - While code generation can boost performance, its use may be problematic in browser contexts enforcing a strict content security policy (CSP). If running in or targeting an environment with a CSP, avoid using code generation.
<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">
import discreteUniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@esm/index.mjs';
import uniform from 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-uniform@esm/index.mjs';
import evalpoly from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-tools-evalpoly@esm/index.mjs';
// Create an array of random coefficients:
var coef = discreteUniform( 10, -100, 100 );
// Evaluate the polynomial at random values:
var v;
var i;
for ( i = 0; i < 100; i++ ) {
v = uniform( 0.0, 100.0 );
console.log( 'f(%d) = %d', v, evalpoly( coef, v ) );
}
// Generate an `evalpoly` function:
var polyval = evalpoly.factory( coef );
for ( i = 0; i < 100; i++ ) {
v = uniform( -50.0, 50.0 );
console.log( 'f(%d) = %d', v, polyval( v ) );
}
</script>
</body>
</html>@stdlib/math-base/tools/evalrational: evaluate a rational function using double-precision floating-point arithmetic.
This package is part of stdlib, a standard library 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.
See LICENSE.
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