feat: add `blas/base/drotmg` #9724

DhruvArvindSingh · 2026-01-13T12:52:52Z

Progresses #2039.

Description

What is the purpose of this pull request?

This pull request:

Adds JS implementation of @stdlib/blas/base/drotmg
Adds Fortran implementation of @stdlib/blas/base/drotmg
Adds C implementation of @stdlib/blas/base/drotmg
Adds Tests , Benchmarks and Examples for C, Fortran and JS

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

progresses [RFC]: Add BLAS bindings and implementations for linear algebra (tracking issue) #2039

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

In this PR i have implemented drotmg main and assign function in C with 6 and 7 arguments respectively

void c_drotmg( const double d1, const double d2, const double x1, const double y1, double *Out, const CBLAS_INT strideOut );

void c_drotmg_assign( const double d1, const double d2, const double x1, const double y1, double *Out, const CBLAS_INT strideOut, const CBLAS_INT offsetOut );

In this PR i have implemented drotmg.f code by taking reference from LAPACK LINK

void drotmg( double *, double *, double *, const double *, double * );

Checklist

Please ensure the following tasks are completed before submitting this pull request.

Read, understood, and followed the contributing guidelines.

AI Assistance

When authoring the changes proposed in this PR, did you use any kind of AI assistance?

Yes
No

If you answered "yes" above, how did you use AI assistance?

Code generation (e.g., when writing an implementation or fixing a bug)
Test/benchmark generation
Documentation (including examples)
Research and understanding

Disclosure

If you answered "yes" to using AI assistance, please provide a short disclosure indicating how you used AI assistance. This helps reviewers determine how much scrutiny to apply when reviewing your contribution. Example disclosures: "This PR was written primarily by Claude Code." or "I consulted ChatGPT to understand the codebase, but the proposed changes were fully authored manually by myself.".

@stdlib-js/reviewers

--- 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: passed - task: lint_package_json status: passed - task: lint_repl_help status: passed - task: lint_javascript_src status: passed - task: lint_javascript_cli status: na - task: lint_javascript_examples status: passed - task: lint_javascript_tests status: passed - task: lint_javascript_benchmarks status: passed - task: lint_python status: na - task: lint_r status: na - task: lint_c_src status: missing_dependencies - task: lint_c_examples status: missing_dependencies - task: lint_c_benchmarks status: missing_dependencies - task: lint_c_tests_fixtures status: na - task: lint_shell status: na - task: lint_typescript_declarations status: passed - task: lint_typescript_tests status: passed - task: lint_license_headers status: passed ---

--- 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: passed - 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 ---

stdlib-bot · 2026-01-13T12:55:39Z

Coverage Report

Package	Statements	Branches	Functions	Lines
blas/base/drotmg	$\color{red}449/497$ $\color{green}+0.00%$	$\color{red}31/34$ $\color{green}+0.00%$	$\color{green}4/4$ $\color{green}+0.00%$	$\color{red}449/497$ $\color{green}+0.00%$

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

Planeshifter

Left some initial comments.

Planeshifter · 2026-01-16T06:29:50Z

lib/node_modules/@stdlib/blas/base/drotmg/lib/assign.js

+// MODULES //
+
+var abs = require( '@stdlib/math/base/special/abs' );
+var isnanf = require( '@stdlib/math/base/assert/is-nanf' );


This is a double-precision function (drotmg), so we should use is-nan instead of is-nanf. The f variant is for single-precision floats.

Suggested change

var isnanf = require( '@stdlib/math/base/assert/is-nanf' );

var isnan = require( '@stdlib/math/base/assert/is-nan' );

And then update the usage on line 69 to use isnan instead of isnanf.

Planeshifter · 2026-01-16T06:30:00Z

lib/node_modules/@stdlib/blas/base/drotmg/lib/assign.js

+		if ( ad1 > ad2 ) {
+			h21 = -y1 / x1;
+			h12 = p2 / p1;
+			u = 1 - ( h12 * h21 );
+			if ( u > 0.0 ) {
+				flag = 0.0;
+				d1 = d1 / u;
+				d2 = d2 / u;
+				x1 = x1 * u;
+			}


Claude Code tells me that this is missing handling for the u <= 0 edge case in this branch and that the Fortran reference implementation (lines 113-126) handles this by setting flag = -1, zeroing out all h values, and zeroing d1, d2, x1. Can you please cross-check the JS implementation against the Fortran code?

Planeshifter · 2026-01-16T06:30:08Z

lib/node_modules/@stdlib/blas/base/drotmg/src/drotmg_assign.c

+		if ( ad1 > ad2 ) {
+			h21 = -y1 / x1;
+			h12 = p2 / p1;
+			u = 1.0 - ( h12 * h21 );
+			if ( u > 0.0 ) {
+				flag = 0.0;
+				d1 = d1 / u;
+				d2 = d2 / u;
+				x1 = x1 * u;
+			}


Same question as in the JavaScript implementation for whether handling for the u <= 0 edge case is missing.

Planeshifter · 2026-01-16T06:30:15Z

lib/node_modules/@stdlib/blas/base/drotmg/include/stdlib/blas/base/drotmg.h

+#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_H
+#define STDLIB_BLAS_EXT_BASE_DROTMG_H


The include guard uses STDLIB_BLAS_EXT_BASE_DROTMG_H but this package is in blas/base/ not blas/ext/base/. Should be STDLIB_BLAS_BASE_DROTMG_H to match other packages like drotm.

Suggested change

#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_H

#define STDLIB_BLAS_EXT_BASE_DROTMG_H

#ifndef STDLIB_BLAS_BASE_DROTMG_H

#define STDLIB_BLAS_BASE_DROTMG_H

Also update line 48 to match.

Planeshifter · 2026-01-16T06:30:22Z

lib/node_modules/@stdlib/blas/base/drotmg/include/stdlib/blas/base/drotmg_cblas.h

+#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H
+#define STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H


Same issue - should use STDLIB_BLAS_BASE_DROTMG_CBLAS_H (no EXT).

Suggested change

#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H

#define STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H

#ifndef STDLIB_BLAS_BASE_DROTMG_CBLAS_H

#define STDLIB_BLAS_BASE_DROTMG_CBLAS_H

Also update line 43 to match.

Planeshifter · 2026-01-16T06:30:29Z

lib/node_modules/@stdlib/blas/base/drotmg/include/stdlib/blas/base/drotmg_fortran.h

+#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H
+#define STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H


Same issue - should use STDLIB_BLAS_BASE_DROTMG_FORTRAN_H (no EXT).

Suggested change

#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H

#define STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H

#ifndef STDLIB_BLAS_BASE_DROTMG_FORTRAN_H

#define STDLIB_BLAS_BASE_DROTMG_FORTRAN_H

Also update line 41 to match.

Planeshifter · 2026-01-16T06:30:35Z

lib/node_modules/@stdlib/blas/base/drotmg/docs/types/index.d.ts

+// TypeScript Version: 4.1
+
+/**
+* Inteface describing `drotmg`.


Small typo: "Inteface" should be "Interface".

Suggested change

* Inteface describing `drotmg`.

* Interface describing `drotmg`.

Planeshifter · 2026-01-16T06:30:44Z

lib/node_modules/@stdlib/blas/base/drotmg/docs/types/index.d.ts

+/**
+* Constructs the parameters for a modified Givens plane rotation.
+*
+* @param d1 - scaling factor for the first vector component
+* @param d2 - scaling factor for the second vector component
+* @param x1 - first component of the first vector
+* @param y1 - first component of the second vector
+* @param out - output array
+* @param stride - index increment
+* @param offset - starting index
+* @returns - output array containing the rotation parameters


The JSDoc for this declaration includes parameters (out, stride, offset) that don't apply to the main function signature - those only apply to the assign method. The main signature is just ( d1, d2, x1, y1 ).

Should be:

/** * Constructs the parameters for a modified Givens plane rotation. * * @param d1 - scaling factor for the first vector component * @param d2 - scaling factor for the second vector component * @param x1 - first component of the first vector * @param y1 - first component of the second vector * @returns - output array containing the rotation parameters * * @example

Planeshifter · 2026-01-16T06:30:51Z

lib/node_modules/@stdlib/blas/base/drotmg/lib/index.js

+var tmp = tryRequire(join(__dirname, './native.js'));
+if (isError(tmp)) {
+	drotmg = main;
+} else {
+	drotmg = tmp;
+}


Missing spaces inside parentheses - stdlib style requires spaces inside function calls. Compare with drotm/lib/index.js:

Suggested change

var tmp = tryRequire(join(__dirname, './native.js'));

if (isError(tmp)) {

drotmg = main;

} else {

drotmg = tmp;

}

var tmp = tryRequire( join( __dirname, './native.js' ) );

if ( isError( tmp ) ) {

drotmg = main;

} else {

drotmg = tmp;

}

DhruvArvindSingh added 2 commits January 13, 2026 18:01

stdlib-bot added BLAS Issue or pull request related to Basic Linear Algebra Subprograms (BLAS). Needs Review A pull request which needs code review. labels Jan 13, 2026

DhruvArvindSingh changed the title ~~Feat/drotmg~~ feat: add blas/base/drotmg Jan 13, 2026

fix: updated copyright years

1db25f0

fix: README.md

169481c

Planeshifter requested changes Jan 16, 2026

View reviewed changes

Planeshifter added Needs Changes Pull request which needs changes before being merged. and removed Needs Review A pull request which needs code review. labels Jan 16, 2026

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feat: add `blas/base/drotmg` #9724

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	var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
	var isnan = require( '@stdlib/math/base/assert/is-nan' );

		#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_H
		#define STDLIB_BLAS_EXT_BASE_DROTMG_H

		#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H
		#define STDLIB_BLAS_EXT_BASE_DROTMG_CBLAS_H

		#ifndef STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H
		#define STDLIB_BLAS_EXT_BASE_DROTMG_FORTRAN_H

	* Inteface describing `drotmg`.
	* Interface describing `drotmg`.

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DhruvArvindSingh commented Jan 13, 2026

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feat: add `blas/base/drotmg` #9724

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stdlib-bot commented Jan 13, 2026 •

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