feat: add `math/base/special/powf` #5739

Neerajpathak07 · 2025-03-02T14:00:38Z

Progresses #649.

Description

What is the purpose of this pull request?

This pull request:

adds math/base/special/powf which is the single-precision version of pow

Related Issues

Does this pull request have any related issues?

This pull request:

progresses [RFC]: Add C implementations to base special math functions (tracking issue) #649

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

Neerajpathak07 · 2025-03-02T14:05:14Z

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

+var polyvalL = require( './polyval_l.js' );
+
+
+// VARIABLES //


these values have been based on upstream implementation of powf in msun.

Neerajpathak07 · 2025-03-02T14:06:59Z

@kgryte @gunjjoshi what do you guys think of the JS implementation so far!!

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

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

Neerajpathak07 · 2025-03-02T14:13:51Z

lib/node_modules/@stdlib/math/base/special/powf/test/test.native.js

have kept this empty as of now thinking of generating fixtures first and get back to this.

lib/node_modules/@stdlib/math/base/special/powf/README.md

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

Neerajpathak07 · 2025-03-05T15:08:54Z

Updates so far cc: @kgryte @gunjjoshi

Went through the binary format for float32 as discussed in the meet and referred documentation for to-uint32, from-binary-string & to-binary-string also studied the documentation for constants/float32 packages.
Changed var names across logx logax and pow2 with accurate hexadecimal values based on upstream implementation with corresponding logical var names.
Based all the JS implementation wrt to powf
used JS var like towordf and forWordf to resonate with GET_FLOAT_WORD & SET_FLOAT_WORD.
reduced the LOG_WORKSPACE from an array of high and low bits to a singular var to compensate 32-bit int!!
wrapped the implementation in float64ToFloat32
reduced CI errors now most of them require C implementation of powf
updated reference link in JS licenses to the msun file for powf
removed the logic for high and low words space and added logic for single variable workspace in main.js

Upcoming updates

adding test fixtures.
Working on test cases.
adding C implementations once the JS one is approved.
Fixing bugs and typo errors.

lib/node_modules/@stdlib/math/base/special/powf/lib/pow2.js

lib/node_modules/@stdlib/math/base/special/powf/lib/log2ax.js

lib/node_modules/@stdlib/math/base/special/powf/lib/pow2.js

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

Neerajpathak07 · 2025-03-05T19:23:58Z

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

+			if ( sn === 1 ) {
+				// Signal overflow...
+				return sn * HUGE * HUGE;
+			}
+			// Signal underflow...
+			return sn * TINY * TINY;


@gunjjoshi was a little confused about handling Over and underflow when x is not close to unity

Neerajpathak07 · 2025-03-06T10:49:10Z

Had to rebase a branch as an unwanted change was added Ik it's unethical to do this but it was messing the purpose of this big-PR everything is running clean now working on more features.

gunjjoshi · 2025-03-07T04:48:20Z

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

+*
+* ## Notice
+*
+* 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/e_powf.c}. The implementation follows the original, but has been modified for JavaScript.


We can update this 9.3.0 version to use the latest implementation.

We can use this: https://svnweb.freebsd.org/base/release/12.2.0/lib/msun/src/e_powf.c

gunjjoshi · 2025-03-07T04:53:45Z

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

+/**
+* Evaluates the exponential function for single-precision values.
+*
+* ## Method


Method is not required here. We can remove this, as it is not present in the reference implementation.

gunjjoshi · 2025-03-07T04:54:34Z

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

+*     x^y = 2^n e^{y^\prime \cdot \mathrm{log2}}
+*     ```
+*
+* ## Special Cases


Similarly, this and the Notes section below can be removed too.

gunjjoshi · 2025-03-07T05:00:23Z

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

+	hx = fromWordf( x );
+	hy = fromWordf( y );


@Neerajpathak07 hx and hy are words, which we are getting from the numbers x and y. So, we should be using toWordf here, instead of fromWordf.

gunjjoshi · 2025-03-07T05:04:37Z

@Neerajpathak07 Let's follow https://svnweb.freebsd.org/base/release/12.2.0/lib/msun/src/e_powf.c?revision=367086&view=markup here. The current implementation in main.js looks a bit off from this reference. You might want to restructure it, so that it matches with the reference.

gunjjoshi · 2025-03-07T05:06:23Z

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

+	}
+
+	// Special cases `x`...
+	if ( lx === 0 ) {


Where is this lx coming from?

Seems like you've done a port of the double-precision implementation. Ideally, we must be independently following the single-precision reference, as the implementations may vary significantly.

@gunjjoshi I haven't started refactoring the main.js yet was working on log2ax, logx and pow2 to get them in line with single-precision implementation and wanted to get approvals on the var names and hexadecimal values first.
What I have changed in main.js is:-

Removed the logic for high and low words.

Align the var with correct package convention.

@Neerajpathak07 I would have started the implementation from main.js, referring to the freeBSD implementation, rather than first working on log2ax, logx and pow2.

Noted I'll keep that in mind.

Neerajpathak07 added 2 commits February 28, 2025 00:25

feat: add basic files

815d266

feat: add js implementation

d890cdc

stdlib-bot added the Math Issue or pull request specific to math functionality. label Mar 2, 2025

Neerajpathak07 commented Mar 2, 2025

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Neerajpathak07 force-pushed the add-powf branch from 54fe31f to d890cdc Compare March 6, 2025 08:18

Neerajpathak07 added 2 commits March 6, 2025 13:59

chore: update modules & var

1f5828a

chore: update modules & var

5e317e0

gunjjoshi requested changes Mar 7, 2025

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gunjjoshi reviewed Mar 7, 2025

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Neerajpathak07 added 2 commits March 12, 2025 19:32

chore: refactoring js implementation

892d7c1

chore: removing lx and hx from special cases

19edd05

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feat: add `math/base/special/powf` #5739

feat: add `math/base/special/powf` #5739

Neerajpathak07 commented Mar 2, 2025 •

edited by gunjjoshi

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feat: add math/base/special/powf #5739

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feat: add math/base/special/powf #5739

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Neerajpathak07 commented Mar 2, 2025 • edited by gunjjoshi Loading

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Neerajpathak07 commented Mar 5, 2025 • edited Loading

Updates so far cc: @kgryte @gunjjoshi

Upcoming updates

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feat: add `math/base/special/powf` #5739

feat: add `math/base/special/powf` #5739

Neerajpathak07 commented Mar 2, 2025 •

edited by gunjjoshi

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