feat: add `number/float16/base/assert/is-almost-same-value` by kaushal-kumar-it · Pull Request #9664 · stdlib-js/stdlib

kaushal-kumar-it · 2026-01-10T05:02:16Z

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Resolves none.

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This pull request:

Adds number/float16/base/assert/is-almost-same-value

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--- 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: 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: passed - task: lint_license_headers status: passed ---

stdlib-bot · 2026-01-10T05:04:27Z

Coverage Report

Package	Statements	Branches	Functions	Lines
number/float16/base/assert/is-almost-same-value	$\color{green}154/154$ $\color{green}+0.00%$	$\color{green}11/11$ $\color{green}+0.00%$	$\color{green}1/1$ $\color{green}+0.00%$	$\color{green}154/154$ $\color{green}+0.00%$

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: na - 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 ---

Planeshifter

Implementation differs in behavior from float32 and float64.

Planeshifter · 2026-01-10T06:01:36Z

lib/node_modules/@stdlib/number/float16/base/assert/is-almost-same-value/lib/main.js

+	// Handle signed zeros (-0 !== +0 in SameValue):
+	if ( isPositiveZero( af ) && isNegativeZero( bf ) ) {
+		return false;
+	}
+	if ( isNegativeZero( af ) && isPositiveZero( bf ) ) {
+		return false;
+	}


This signed zero handling behaves differently from the float32 and float64 equivalents.

The float32 is-almost-same-value only distinguishes between +0 and -0 when maxULP === 0. When maxULP >= 1, it returns true for (0.0, -0.0) because they're 0 ULPs apart (per ulp-difference).

Currently this implementation always returns false for +0 vs -0 regardless of maxULP, which creates an inconsistency:

// float32 behavior: isAlmostSameValue(0.0, -0.0, 0); // false isAlmostSameValue(0.0, -0.0, 1); // true // float16 behavior (this PR): isAlmostSameValue(0.0, -0.0, 0); // false isAlmostSameValue(0.0, -0.0, 1); // false (inconsistent!)

Check the float32 and float64 implementations for what is expected.

@Planeshifter I noticed that the float32 implementation uses isSameValue as a dependency:
Should I:
Implement is-same-value for float16 first, then update this PR to match the float32 pattern exactly? This would maintain consistency across the codebase.
Keep the current self-contained implementation that uses the 1/x approch directly for signed zeros without depending on is-same-value?

Planeshifter · 2026-01-10T06:01:45Z

lib/node_modules/@stdlib/number/float16/base/assert/is-almost-same-value/test/test.js

+tape( 'the function returns `false` if signed zeros are provided as input values irrespective of the specified number of ULPs', function test( t ) {
+	t.strictEqual( isAlmostSameValue( 0.0, -0.0, 0 ), false, 'returns expected value' );
+	t.strictEqual( isAlmostSameValue( -0.0, 0.0, 0 ), false, 'returns expected value' );
+	t.strictEqual( isAlmostSameValue( 0.0, -0.0, 1 ), false, 'returns expected value' );
+	t.strictEqual( isAlmostSameValue( -0.0, 0.0, 1 ), false, 'returns expected value' );
+	t.end();
+});


The test description and expectations for maxULP >= 1 don't match the float32 equivalent's behavior. The float32 version returns true when comparing +0 and -0 with maxULP >= 1, because they're 0 ULPs apart.

If aligning with float32, these tests should be:

Suggested change

tape( 'the function returns `false` if signed zeros are provided as input values irrespective of the specified number of ULPs', function test( t ) {

t.strictEqual( isAlmostSameValue( 0.0, -0.0, 0 ), false, 'returns expected value' );

t.strictEqual( isAlmostSameValue( -0.0, 0.0, 0 ), false, 'returns expected value' );

t.strictEqual( isAlmostSameValue( 0.0, -0.0, 1 ), false, 'returns expected value' );

t.strictEqual( isAlmostSameValue( -0.0, 0.0, 1 ), false, 'returns expected value' );

t.end();

});

tape( 'the function distinguishes between signed zeros when the specified number of ULPs is zero', function test( t ) {

t.strictEqual( isAlmostSameValue( 0.0, -0.0, 0 ), false, 'returns expected value' );

t.strictEqual( isAlmostSameValue( -0.0, 0.0, 0 ), false, 'returns expected value' );

t.strictEqual( isAlmostSameValue( 0.0, -0.0, 1 ), true, 'returns expected value' );

t.strictEqual( isAlmostSameValue( -0.0, 0.0, 1 ), true, 'returns expected value' );

t.end();

});

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Neerajpathak07 · 2026-01-12T03:56:26Z

lib/node_modules/@stdlib/number/float16/base/assert/is-almost-same-value/lib/main.js

+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var f16 = require( '@stdlib/number/float64/base/to-float16' );
+var ulpdiff = require( '@stdlib/number/float16/base/ulp-difference' );


Suggested change

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

var f16 = require( '@stdlib/number/float64/base/to-float16' );

var ulpdiff = require( '@stdlib/number/float16/base/ulp-difference' );

var isnan = require( '@stdlib/number/float16/base/assert/is-nan' );

var isSameValue = require( '@stdlib/number/float16/base/assert/is-same-value' );

var ulpdiff = require( '@stdlib/number/float16/base/ulp-difference' );

Handling -+0 and isnan should come form isSameValue
Should be resolved once #9677 is merged.

Neerajpathak07 · 2026-01-12T03:58:46Z

lib/node_modules/@stdlib/number/float16/base/assert/is-almost-same-value/lib/main.js

+	var af;
+	var bf;
+
+	af = f16( a );
+	bf = f16( b );
+
+	// Check for NaN (NaN is considered equal to NaN in SameValue):
+	if ( isnan( af ) && isnan( bf ) ) {
+		return true;
+	}
+	// Only distinguish signed zeros when maxULP is 0:
+	if ( maxULP === 0 && af === 0.0 && bf === 0.0 ) {
+		return ( 1.0 / af === 1.0 / bf );
+	}
+	// Check if exactly equal:
+	if ( af === bf ) {
+		return true;
+	}


Suggested change

var af;

var bf;

af = f16( a );

bf = f16( b );

// Check for NaN (NaN is considered equal to NaN in SameValue):

if ( isnan( af ) && isnan( bf ) ) {

return true;

}

// Only distinguish signed zeros when maxULP is 0:

if ( maxULP === 0 && af === 0.0 && bf === 0.0 ) {

return ( 1.0 / af === 1.0 / bf );

}

// Check if exactly equal:

if ( af === bf ) {

return true;

}

if ( isnan( a ) || isnan( b ) || maxULP === 0 ) {

return isSameValue( a, b );

}

Better to use the explicit float16 version of isnan rather than converting to half-precision

Neerajpathak07 · 2026-01-12T04:03:05Z

lib/node_modules/@stdlib/number/float16/base/assert/is-almost-same-value/README.md

+var bool = isAlmostSameValue( 1.0, 1.0+EPS, 1 );
+console.log( bool );
+// => true
+
+bool = isAlmostSameValue( 1.0+EPS, 1.0, 1 );
+console.log( bool );
+// => true
+
+bool = isAlmostSameValue( 1.0, 1.0+EPS+EPS, 1 );
+console.log( bool );
+// => false
+
+bool = isAlmostSameValue( 1.0, 1.0+EPS, 0 );
+console.log( bool );
+// => false
+
+bool = isAlmostSameValue( -0.0, 0.0, 0 );
+console.log( bool );
+// => false
+
+bool = isAlmostSameValue( 1.0, NaN, 1 );
+console.log( bool );
+// => false
+
+bool = isAlmostSameValue( NaN, NaN, 1 );
+console.log( bool );
+// => true
+```


Suggested change

var bool = isAlmostSameValue( 1.0, 1.0+EPS, 1 );

console.log( bool );

// => true

bool = isAlmostSameValue( 1.0+EPS, 1.0, 1 );

console.log( bool );

// => true

bool = isAlmostSameValue( 1.0, 1.0+EPS+EPS, 1 );

console.log( bool );

// => false

bool = isAlmostSameValue( 1.0, 1.0+EPS, 0 );

console.log( bool );

// => false

bool = isAlmostSameValue( -0.0, 0.0, 0 );

console.log( bool );

// => false

bool = isAlmostSameValue( 1.0, NaN, 1 );

console.log( bool );

// => false

bool = isAlmostSameValue( NaN, NaN, 1 );

console.log( bool );

// => true

```

var bool = isAlmostSameValue( 1.0, 1.0+EPS, 1 );

// returns true

bool = isAlmostSameValue( 1.0+EPS, 1.0, 1 );

// returns true

bool = isAlmostSameValue( 1.0, 1.0+EPS+EPS, 1 );

// returns false

bool = isAlmostSameValue( 1.0, 1.0+EPS, 0 );

// returns false

bool = isAlmostSameValue( -0.0, 0.0, 0 );

// returns false

bool = isAlmostSameValue( 1.0, NaN, 1 );

// returns false

bool = isAlmostSameValue( NaN, NaN, 1 );

// returns true

Let's remove the console.log in the markdown.

ref:- https://github.com/stdlib-js/stdlib/blob/develop/lib/node_modules/%40stdlib/number/float16/base/assert/is-almost-equal/README.md#examples

stdlib-bot added the Needs Review A pull request which needs code review. label Jan 10, 2026

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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 10, 2026

kaushal-kumar-it requested a review from Planeshifter January 10, 2026 06:39

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kaushal-kumar-it added 2 commits January 10, 2026 13:50

Neerajpathak07 reviewed Jan 12, 2026

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feat: add `number/float16/base/assert/is-almost-same-value`#9664

feat: add `number/float16/base/assert/is-almost-same-value`#9664
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