feat: add math/base/special/floornf

[gururaj1512]

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Resolves a part of #649 .

Description

What is the purpose of this pull request?

This pull request:

• Adds javascript and C implementation for math/base/special/floornf

Related Issues

Does this pull request have any related issues?

This pull request:

• Resolves a part of [RFC]: Add C implementations to base special math functions (tracking issue) #649 .

Other

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

• Implementation ideally should use powf. Due to unavailablity used inbuilt function of powf from <math.h>.

Checklist

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

• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[gururaj1512]

/stdlib help

[gururaj1512]

/stdlib merge

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/floornf	$\color{red}274/276$ $\color{green}+0.00%$	$\color{red}22/23$ $\color{green}+0.00%$	$\color{green}2/2$ $\color{green}+0.00%$	$\color{red}274/276$ $\color{green}+0.00%$

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

[kgryte]

/stdlib merge

[kgryte]

@anandkaranubc Would you mind reviewing this PR and helping get it over the finish line? Cheers!

[anandkaranubc]

/stdlib merge

[anandkaranubc]

@gururaj1512 Did you use any reference implementation for this?

[kgryte]

@anandkaranubc Yes, he seemed to use our floorn implementation: https://github.com/stdlib-js/stdlib/blob/develop/lib/node_modules/%40stdlib/math/base/special/floorn/lib/main.js.

Meaning, this is in-house.

[kgryte]

@anandkaranubc While powf would be acceptable, the use of exp10f (which we don't currently have implemented) may be better (i.e., faster).

[kgryte]

@anandkaranubc Ref: #7387

[kgryte]

We can address this in a follow-up PR once #7387 is merged.

[anandkaranubc]

PR looks to be in good shape. 🚀

[kgryte]

@anandkaranubc It's a little odd that we need ulpdiff tests here, given that the results are integers and rounded to the nearest 100. Is there something I am missing?

[anandkaranubc]

Agreed. It’s because the powf operation doesn’t yield an exact result for s = powf( f32( 10.0 ), -n ); (with n = 3).

Ref:

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

Line 158 in 7cd6cec

s = powf( f32( 10.0 ), -n );

The result here is 0.0010000000474974513, which then trickles down to line 163, where the division by s yields a slightly inexact result (11999.9990234375).

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

Line 163 in 7cd6cec

return f32( floorf( y ) / s );

[kgryte]

Well, I suppose we mention this possibility in the README. Namely that results may be inexact. Thanks for the explanation.

[kgryte]

Apart from updating the main example and a question regarding a couple of tests, this PR is looking good.

[kgryte]

LGTM