Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 6x 6x 6x 6x 6x 6x 6x 6x 6x 6x 1x 1x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 6x 1x 1x 4x 4x 1x 1x 3x 3x 3x 3x 3x 3x 3x 3x 5x 5x 5x 5x 3x 3x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 5x 1x 1x 6x 3x 3x 3x 3x 3x | /**
* @license Apache-2.0
*
* Copyright (c) 2026 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var float64ToFloat32 = require( '@stdlib/number/float64/base/to-float32' );
var Float32Array = require( '@stdlib/array/float32' );
var Fcn = require( '@stdlib/function/ctor' );
var chebyshevSeriesf = require( './main.js' );
// MAIN //
/**
* Generates a function for evaluating a Chebyshev series.
*
* ## Notes
*
* - The compiled function uses [Clenshaw's algorithm][clenshaw-algorithm] for efficient computation.
*
* [clenshaw-algorithm]: https://en.wikipedia.org/wiki/Clenshaw_algorithm
*
* @param {NumericArray} c - Chebyshev series coefficients in descending degree order
* @returns {Function} function for evaluating a Chebyshev series
*
* @example
* var Float32Array = require( '@stdlib/array/float32' );
*
* var polyval = factory( new Float32Array( [ 1.0, 0.5 ] ) );
*
* var v = polyval( 1.0 ); // 1*T_0(1/2) + 0.5*T_1(1/2)
* // returns 0.75
*
* v = polyval( 0.0 ); // 1*T_0(0) + 0.5*T_1(0)
* // returns 0.25
*/
function factory( c ) {
var f;
var n;
var i;
// Explicitly copy in order to ensure single-precision:
c = new Float32Array( c );
// Use the general implementation if the number of coefficients is large:
if ( c.length > 500 ) {
return evaluate;
}
// Code generation. Start with the function definition...
f = 'return function chebyshevSeriesf(x){';
f += 'var b0;';
f += 'var b1;';
f += 'var b2;';
// Create the function body...
n = c.length;
// If no coefficients, the function always returns zero...
if ( n === 0 ) {
f += 'return 0.0;';
}
// If only one coefficient, the function always returns that coefficient divided by two...
else if ( n === 1 ) {
f += 'return f64_to_f32(0.5 * ' + c[ 0 ] + ');';
}
// If more than one coefficient, apply Clenshaw's algorithm...
else {
// Initialize:
f += 'b0 = ' + c[ 0 ] + ';';
f += 'b1 = 0.0;';
// Recurrence:
for ( i = 1; i < n; i++ ) {
f += 'b2 = b1;';
f += 'b1 = b0;';
f += 'b0 = f64_to_f32(f64_to_f32(f64_to_f32(x*b1) - b2) + ' + c[ i ] + ');';
}
f += 'return f64_to_f32(0.5 * f64_to_f32(b0 - b2));';
}
// Close the function:
f += '};';
// Add a source directive for debugging:
f += '//# sourceURL=chebyshevSeriesf.factory.js';
// Create the function in the global scope:
return ( new Fcn( 'f64_to_f32', f ) )( float64ToFloat32 );
/**
* Evaluates a Chebyshev series.
*
* @private
* @param {number} x - evaluation point
* @returns {number} evaluated series
*/
function evaluate( x ) {
return chebyshevSeriesf( x, c );
}
}
// EXPORTS //
module.exports = factory;
|