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Neerajpathak07Neerajpathak07
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feat: add js implementation
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‎lib/node_modules/@stdlib/math/base/special/powf/lib/index.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2025 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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/**
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* Evaluate the exponential function for single-precision values.
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*
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* @module @stdlib/math/base/special/powf
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*
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* @example
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* var powf = require( '@stdlib/math/base/special/powf' );
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*
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* var v = powf( 2.0, 3.0 );
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* // returns 8.0
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*
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* v = powf( 4.0, 0.5 );
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* // returns 2.0
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*
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* v = powf( 100.0, 0.0 );
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* // returns 1.0
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*
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* v = powf( 3.1415927410125732, 5.0 );
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* // returns ~306.0197
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*
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* v = powf( 3.1415927410125732, -0.2 );
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* // returns ~0.7954
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*
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* v = powf( NaN, 3.0 );
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* // returns NaN
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*
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* v = powf( 5.0, NaN );
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* // returns NaN
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*
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* v = powf( NaN, NaN );
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* // returns NaN
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*/
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// MODULES //
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var main = require( '@stdlib/math/base/special/powf/lib/log2axf' );
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// EXPORTS //
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module.exports = main;

‎lib/node_modules/@stdlib/math/base/special/powf/lib/log2axf.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2025 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*
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* ## Notice
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*
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* The following copyright and license were part of the original implementation available as part of [FreeBSD]{@link https://svnweb.freebsd.org/base/release/9.3.0/lib/msun/src/s_pow.c}. The implementation follows the original, but has been modified for JavaScript.
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*
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* ```text
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* Copyright (C) 2004 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ```
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*/
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'use strict';
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// MODULES //
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var getHighWord = require( '@stdlib/number/float32/base/get-high-word' );
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var setLowWord = require( '@stdlib/number/float32/base/set-low-word' );
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var setHighWord = require( '@stdlib/number/float32/base/set-high-word' );
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var BIAS = require( '@stdlib/constants/float32/exponent-bias' );
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var HIGH_NUM_SIGNIFICAND_BITS = require( '@stdlib/constants/float32/num-high-word-significand-bits' );
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var polyvalL = require( './polyval_l.js' );
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// VARIABLES //
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// 0x000fffff = 1048575 => 0 00000000000 11111111111111111111
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var HIGH_SIGNIFICAND_MASK = 0x007FFFFF|0; // asm type annotation
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// 0x00100000 = 1048576 => 0 00000000001 00000000000000000000 => biased exponent: 1 = -1022+1023 => 2^-1022
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var HIGH_MIN_NORMAL_EXP = 0x00800000|0; // asm type annotation
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// 0x3ff00000 = 1072693248 => 0 01111111111 00000000000000000000 => biased exponent: 1023 = 0+1023 => 2^0 = 1
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var HIGH_BIASED_EXP_0 = 0x3F800000|0; // asm type annotation
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// 0x20000000 = 536870912 => 0 01000000000 00000000000000000000 => biased exponent: 512 = -511+1023
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var HIGH_BIASED_EXP_NEG_512 = 0x20000000|0; // asm type annotation
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// 0x00080000 = 524288 => 0 00000000000 10000000000000000000
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var HIGH_SIGNIFICAND_HALF = 0x00400000|0; // asm type annotation
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var TWO24 = 16777216.0; // 0x4b800000
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// 2/(3*LN2)
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var CP = 9.6179670095e-01; /* 0x3f76384f =2/(3ln2) */
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// (float)CP
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var CP_HI = 9.6191406250e-01; /* 0x3f764000 =12b cp */
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// Low: CP_HI
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var CP_LO = -1.1736857402e-04; /* 0xb8f623c6 =tail of CP_HI */
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var BP = [
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1.0,
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1.5
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];
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var DP_HI = [
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0.0,
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5.84960938e-01 // 0x3f15c000
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];
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var DP_LO = [
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0.0,
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1.56322085e-06 // 0x35d1cfdc
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];
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// MAIN //
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/**
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* Computes \\(\operatorname{log2f}(ax)\\).
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*
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* @private
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* @param {Array} out - output array
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* @param {number} ax - absolute value of `x`
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* @param {number} ahx - high word of `ax`
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* @returns {Array} output array containing a tuple comprised of high and low parts
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*
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* @example
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* var t = log2axf( [ 0.0, 0.0 ], 9.0, 1075970048 ); // => [ t1, t2 ]
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* // returns [ 3.169923782348633, 0.0000012190936795504075 ]
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*/
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function log2axf( out, ax, ahx ) {
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var tmp;
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var ss; // `hs + ls`
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var s2; // `ss` squared
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var hs;
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var ls;
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var ht;
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var lt;
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var bp; // `BP` constant
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var dp; // `DP` constant
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var hp;
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var lp;
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var hz;
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var lz;
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var t1;
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var t2;
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var t;
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var r;
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var u;
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var v;
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var n;
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var j;
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var k;
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n = 0|0; // asm type annotation
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// Check if `x` is subnormal...
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if ( ahx < HIGH_MIN_NORMAL_EXP ) {
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ax *= TWO24;
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n -= 24|0; // asm type annotation
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ahx = getHighWord( ax );
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}
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// Extract the unbiased exponent of `x`:
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n += ((ahx >> HIGH_NUM_SIGNIFICAND_BITS) - BIAS)|0; // asm type annotation
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// Isolate the significand bits of `x`:
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j = (ahx & HIGH_SIGNIFICAND_MASK)|0; // asm type annotation
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// Normalize `ahx` by setting the (biased) exponent to `1023`:
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ahx = (j | HIGH_BIASED_EXP_0)|0; // asm type annotation
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// Determine the interval of `|x|` by comparing significand bits...
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// |x| < sqrt(3/2)
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if ( j <= 0x3988E ) { // 0 00000000000 00111001100010001110
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k = 0;
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}
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// |x| < sqrt(3)
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else if ( j < 0xBB67A ) { // 0 00000000000 10111011011001111010
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k = 1;
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}
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// |x| >= sqrtf(3)
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else {
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k = 0;
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n += 1|0; // asm type annotation
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ahx -= HIGH_MIN_NORMAL_EXP;
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}
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// Load the normalized high word into `|x|`:
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ax = setHighWord( ax, ahx );
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// Compute `ss = hs + ls = (x-1)/(x+1)` or `(x-1.5)/(x+1.5)`:
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bp = BP[ k ]; // BP[0] = 1.0, BP[1] = 1.5
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u = ax - bp; // (x-1) || (x-1.5)
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v = 1.0 / (ax + bp); // 1/(x+1) || 1/(x+1.5)
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ss = u * v;
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hs = setLowWord( ss, 0 ); // set all low word (less significant significand) bits to 0s
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// Compute `ht = ax + bp` (via manipulation, i.e., bit flipping, of the high word):
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tmp = ((ahx>>1) | HIGH_BIASED_EXP_NEG_512) + HIGH_SIGNIFICAND_HALF;
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tmp += (k << 18); // `(k<<18)` can be considered the word equivalent of `1.0` or `1.5`
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ht = setHighWord( 0.0, tmp );
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lt = ax - (ht - bp);
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ls = v * ( ( u - (hs*ht) ) - ( hs*lt ) );
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// Compute `log(ax)`...
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s2 = ss * ss;
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r = s2 * s2 * polyvalL( s2 );
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r += ls * (hs + ss);
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s2 = hs * hs;
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ht = 3.0 + s2 + r;
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ht = setLowWord( ht, 0 );
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lt = r - ((ht-3.0) - s2);
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// u+v = ss*(1+...):
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u = hs * ht;
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v = ( ls*ht ) + ( lt*ss );
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// 2/(3LN2) * (ss+...):
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hp = u + v;
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hp = setLowWord( hp, 0 );
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lp = v - (hp - u);
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hz = CP_HI * hp; // CP_HI+CP_LO = 2/(3*LN2)
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lz = ( CP_LO*hp ) + ( lp*CP ) + DP_LO[ k ];
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// log2(ax) = (ss+...)*2/(3*LN2) = n + dp + hz + lz
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dp = DP_HI[ k ];
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t = n;
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t1 = ((hz+lz) + dp) + t; // log2(ax)
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t1 = setLowWord( t1, 0 );
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t2 = lz - (((t1-t) - dp) - hz);
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out[ 0 ] = t1;
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out[ 1 ] = t2;
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return out;
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}
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// EXPORTS //
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module.exports = log2axf;

‎lib/node_modules/@stdlib/math/base/special/powf/lib/logxf.js

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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*
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* ## Notice
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*
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* The following copyright and license were part of the original implementation available as part of [FreeBSD]{@link https://svnweb.freebsd.org/base/release/9.3.0/lib/msun/src/s_pow.c}. The implementation follows the original, but has been modified for JavaScript.
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*
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* ```text
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* Copyright (C) 2004 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ```
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*/
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'use strict';
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// MODULES //
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var setLowWord = require( '@stdlib/number/float64/base/set-low-word' );
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var polyvalW = require( './polyval_w.js' );
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// VARIABLES //
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// 1/LN2
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var INV_LN2 = 1.4426950216e+00; // 0x3fb8aa3b =1/ln2
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// High (24 bits): 1/LN2
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var INV_LN2_HI = 1.4426879883e+00; // 0x3fb8aa00 =16b 1/ln2
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// Low: 1/LN2
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var INV_LN2_LO = 7.0526075433e-06; // 0x36eca570 =1/ln2 tail
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// MAIN //
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/**
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* Computes \\(\operatorname{log}(x)\\) assuming \\(|1-x|\\) is small and using the approximation \\(x - x^2/2 + x^3/3 - x^4/4\\).
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*
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* @private
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* @param {Array} out - output array
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* @param {number} ax - absolute value of `x`
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* @returns {Array} output array containing a tuple comprised of high and low parts
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*
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* @example
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* var t = logxf( [ 0.0, 0.0 ], 9.0 );
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* // Expected output: [ -1265.7236328125, -0.0008163940840404393 ]
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*/
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function logxf( out, ax ) {
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var t2;
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var t1;
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var t;
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var w;
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var u;
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var v;
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t = ax - 1.0; // `t` has `20` trailing zeros
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w = t * t * polyvalW( t );
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u = INV_LN2_HI * t; // `INV_LN2_HI` has `21` significant bits
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v = ( t*INV_LN2_LO ) - ( w*INV_LN2 );
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t1 = u + v;
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t1 = setLowWord( t1, 0 );
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t2 = v - (t1 - u);
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out[ 0 ] = t1;
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out[ 1 ] = t2;
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return out;
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}
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// EXPORTS //
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module.exports = logxf;

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