feat: add blas/ext/base/ndarray/dapx

[ujjwalv01]

Resolves a part of #14404

Description

What is the purpose of this pull request?

This pull request:

• Implements the ndarray API wrapper for @stdlib/blas/ext/base/dapx (adds a scalar constant to each element in a one-dimensional double-precision floating-point ndarray).
• Ensures consistency with the canonical scalar-operation examples and tests used across the @stdlib/blas/ext/base packages.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: add ndarray interface variants for missing modules in @stdlib/blas/ext/base #14404

Questions

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No.

Other

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No.

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?

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• 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.".

I used an AI assistant to research existing ndarray packages to ensure consistency with canonical example arrays (e.g., [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] for scalar operations) and to help scaffold the tests and benchmarks. All changes were manually verified and aligned with the blas/ext/base/dapx reference tests.

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/ndarray/dapx	$\\color{green}120/120$ $\\color{green}+0.00\\%$	$\\color{green}3/3$ $\\color{green}+0.00\\%$	$\\color{green}1/1$ $\\color{green}+0.00\\%$	$\\color{green}120/120$ $\\color{green}+0.00\\%$

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

[0PrashantYadav0]

I think these changes are required as of now.

[ujjwalv01]

Hi @0PrashantYadav0

I've applied the suggestions, but the CI is failing with a data type cast error. It seems that passing a plain array to @stdlib/ndarray/array infers it as a generic dtype, and casting from generic to float64 is not allowed under the default safe casting mode;

To fix this, should I wrap the input in a Float64Array like this?
var x = array( new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] ), { 'dtype': 'float64' });

Or would you prefer I add 'ndmin': 1, 'cast': 'unsafe' to the options? LMK which pattern, or anything else, is preferred;

[0PrashantYadav0]

Agreed, var x = array( new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] ) ); makes much more sense. I considered this approach initially but held off because it requires multiple passes. Before we move forward with this change, let's get @kgryte 's review.

[kgryte]

Left initial comments.