feat: add `fft/base/fftpack/decompose` by gunjjoshi · Pull Request #10354 · stdlib-js/stdlib

gunjjoshi · 2026-02-18T17:35:41Z

Resolves None.

Description

What is the purpose of this pull request?

This pull request:

adds fft/base/fftpack/decompose, which is a part of fftpack.
is an extension of feat: add initial implementation of fft/base/fftpack #4121.

This package decomposes a number (sequence length in the context of FFT) into its factors, so that we can process the smaller sequences independently, rather than processing the whole sequence length at once, during the fast Fourier transform.

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Test coverage report:

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Read, understood, and followed the contributing guidelines.

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Used AI to suggest test cases that can be implemented.

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…decompose

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stdlib-bot · 2026-02-18T17:38:08Z

Coverage Report

Package	Statements	Branches	Functions	Lines
fft/base/fftpack/decompose	$\color{green}266/266$ $\color{green}+0.00%$	$\color{green}23/23$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}266/266$ $\color{green}+0.00%$

The above coverage report was generated for the changes in this PR.

--- type: pre_commit_static_analysis_report description: Results of running static analysis checks when committing changes. report: - task: lint_filenames status: passed - task: lint_editorconfig status: passed - task: lint_markdown status: na - task: lint_package_json status: na - task: lint_repl_help status: na - task: lint_javascript_src status: na - task: lint_javascript_cli status: na - task: lint_javascript_examples status: na - task: lint_javascript_tests status: passed - task: lint_javascript_benchmarks status: na - task: lint_python status: na - task: lint_r status: na - task: lint_c_src status: na - task: lint_c_examples status: na - task: lint_c_benchmarks status: na - task: lint_c_tests_fixtures status: na - task: lint_shell status: na - task: lint_typescript_declarations status: passed - task: lint_typescript_tests status: na - task: lint_license_headers status: passed ---

kgryte · 2026-02-18T19:21:01Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/docs/types/index.d.ts

+* var f = factors.slice();
+* // returns [ 630, 5, 2, 3, 3, 5, 7 ]
+*/
+declare function decompose( N: number, initial: Array<number>, out: Array<number>, stride: number, offset: number ): number;


Suggested change

declare function decompose( N: number, initial: Array<number>, out: Array<number>, stride: number, offset: number ): number;

declare function decompose( N: number, initial: Collection<number>, out: Collection<number>, stride: number, offset: number ): number;

kgryte · 2026-02-18T19:25:28Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/lib/main.js

+	var i;
+	var j;
+
+	if ( !isNonNegativeInteger( N ) || !isNonNegativeIntegerArray( initial ) ||


This can be removed.

kgryte · 2026-02-18T19:28:13Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/README.md

+
+-   The function mutates the input array.


Suggested change

- The function mutates the input array.

kgryte · 2026-02-18T19:29:04Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/lib/main.js

+* var f = factors.slice();
+* // returns [ 8, 2, 2, 4 ]
+*/
+function decompose( N, initial, out, stride, offset ) {


Suggested change

function decompose( N, initial, out, stride, offset ) {

function decompose( N, M, initial, strideInitial, offsetInitial, out, strideOut, offsetOut ) {

where M is the number of trial divisors and initial is a strided array.

kgryte · 2026-02-18T19:30:48Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/lib/main.js

+*
+* -   The function mutates the input array.


Suggested change

*

* - The function mutates the input array.

kgryte · 2026-02-18T19:30:58Z

lib/node_modules/@stdlib/fft/base/fftpack/decompose/lib/main.js

+*
+* ## Notes
+*
+* -   Factorization results are stored in the input array as follows:


Suggested change

* - Factorization results are stored in the input array as follows:

* - Factorization results are stored in the output array as follows:

gunjjoshi added 3 commits February 18, 2026 22:47

Merge branch 'decompose' of https://github.com/gunjjoshi/stdlib into …

c765d85

…decompose

stdlib-bot added the Needs Review A pull request which needs code review. label Feb 18, 2026

kgryte reviewed Feb 18, 2026

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feat: add `fft/base/fftpack/decompose`#10354

feat: add `fft/base/fftpack/decompose`#10354
gunjjoshi wants to merge 4 commits intostdlib-js:developfrom
gunjjoshi:decompose

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	declare function decompose( N: number, initial: Array<number>, out: Array<number>, stride: number, offset: number ): number;
	declare function decompose( N: number, initial: Collection<number>, out: Collection<number>, stride: number, offset: number ): number;

	function decompose( N, initial, out, stride, offset ) {
	function decompose( N, M, initial, strideInitial, offsetInitial, out, strideOut, offsetOut ) {

	* - Factorization results are stored in the input array as follows:
	* - Factorization results are stored in the output array as follows:

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gunjjoshi commented Feb 18, 2026

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