feat: add math/base/special/frexpf

PR-URL: #7089
Ref: #649

Reviewed-by: Philipp Burckhardt <[email protected]>
Signed-off-by: Karan Anand <[email protected]>

Author: anandkaranubc

lib/node_modules/@stdlib/math/base/special/frexpf/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2025 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# frexpf
+
+> Split a [single-precision floating-point number][ieee754] into a normalized fraction and an integer power of two.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var frexpf = require( '@stdlib/math/base/special/frexpf' );
+```
+
+#### frexpf( x )
+
+Splits a [single-precision floating-point number][ieee754] into a normalized fraction and an integer power of two.
+
+```javascript
+var out = frexpf( 4.0 );
+// returns [ 0.5, 3 ]
+```
+
+By default, the function returns the normalized fraction and the exponent as a two-element `array`. The normalized fraction and exponent satisfy the relation `x = frac * 2^exp`.
+
+```javascript
+var pow = require( '@stdlib/math/base/special/pow' );
+
+var x = 4.0;
+var out = frexpf( x );
+// returns [ 0.5, 3 ]
+
+var frac = out[ 0 ];
+var exp = out[ 1 ];
+
+var bool = ( x === frac * pow(2.0, exp) );
+// returns true
+```
+
+If provided positive or negative zero, `NaN`, or positive or negative `infinity`, the function returns a two-element `array` containing the input value and an exponent equal to `0`.
+
+```javascript
+var out = frexpf( 0.0 );
+// returns [ 0.0, 0 ]
+
+out = frexpf( -0.0 );
+// returns [ -0.0, 0 ]
+
+out = frexpf( NaN );
+// returns [ NaN, 0 ]
+
+out = frexpf( Infinity );
+// returns [ Infinity, 0 ]
+
+out = frexpf( -Infinity );
+// returns [ -Infinity, 0 ]
+```
+
+For all other numeric input values, the [absolute value][@stdlib/math/base/special/absf] of the normalized fraction resides on the interval `[0.5,1)`.
+
+#### frexpf.assign( x, out, stride, offset )
+
+Splits a [single-precision floating-point number][ieee754] into a normalized fraction and an integer power of two and assigns results to a provided output array.
+
+```javascript
+var Float32Array = require( '@stdlib/array/float32' );
+
+var out = new Float32Array( 2 );
+
+var y = frexpf.assign( 4.0, out, 1, 0 );
+// returns <Float32Array>[ 0.5, 3 ]
+
+var bool = ( y === out );
+// returns true
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   Care should be taken when reconstituting a [single-precision floating-point number][ieee754] from a normalized fraction and an exponent. For example,
+
+    ```javascript
+    var pow = require( '@stdlib/math/base/special/pow' );
+    var f32 = require( '@stdlib/number/float64/base/to-float32' );
+
+    var x = 1.7014118346046923e+38; // x ~ 2^127
+
+    var out = frexpf( x );
+    // returns [ 0.5, 128 ]
+
+    // Naive reconstitution:
+    var y = f32( out[ 0 ] * f32( pow( 2.0, out[ 1 ] ) ) );
+    // returns Infinity
+
+    // Account for 2^128 evaluating as infinity by recognizing 2^128 = 2^1 * 2^127:
+    y = f32( out[ 0 ] * f32( pow( 2.0, out[1]-127 ) ) * f32( pow( 2.0, 127 ) ) );
+    // returns 1.7014118346046923e+38
+    ```
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var roundf = require( '@stdlib/math/base/special/roundf' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var f32 = require( '@stdlib/number/float64/base/to-float32' );
+var BIAS = require( '@stdlib/constants/float32/exponent-bias' );
+var frexpf = require( '@stdlib/math/base/special/frexpf' );
+
+var sign;
+var frac;
+var exp;
+var x;
+var f;
+var v;
+var i;
+
+// Generate random numbers and break each into a normalized fraction and an integer power of two...
+for ( i = 0; i < 100; i++ ) {
+    if ( randu() < 0.5 ) {
+        sign = f32( -1.0 );
+    } else {
+        sign = f32( 1.0 );
+    }
+    frac = f32( randu()*10.0 );
+    exp = roundf( randu()*76.0 ) - 38;
+    x = f32( sign * frac * f32( pow( 10.0, exp ) ) );
+    f = frexpf( x );
+    if ( f[ 1 ] > BIAS ) {
+        v = f32( f[ 0 ] * f32( pow(2.0, f[1]-BIAS) ) * f32( pow(2.0, BIAS) ) );
+    } else {
+        v = f32( f[ 0 ] * f32( pow( 2.0, f[ 1 ] ) ) );
+    }
+    console.log( '%d = %d * 2^%d = %d', x, f[ 0 ], f[ 1 ], v );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- C interface documentation. -->
+
+* * *
+
+<section class="c">
+
+## C APIs
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/math/base/special/frexpf.h"
+```
+
+#### stdlib_base_frexpf( x, frac, exp )
+
+Splits a [single-precision floating-point number][ieee754] into a normalized fraction and an integer power of two.
+
+```c
+#include <stdint.h>
+
+float frac;
+int32_t exp;
+stdlib_base_frexpf( 4.0f, &frac, &exp );
+```
+
+The function accepts the following arguments:
+
+-   **x**: `[in] float` input value.
+-   **frac**: `[out] float*` destination for the normalized fraction.
+-   **exp**: `[out] int32_t*` destination for the integer power of two.
+
+```c
+void stdlib_base_frexpf( const float x, float *frac, int32_t *exp );
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- C API usage examples. -->
+
+<section class="examples">
+
+### Examples
+
+```c
+#include "stdlib/math/base/special/frexpf.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+
+int main( void ) {
+    const float x[] = { 4.0f, 0.0f, -0.0f, 1.0f, -1.0f, 3.14f, -3.14f, 1.0e38f, -1.0e38f, 1.0f/0.0f, -1.0f/0.0f, 0.0f/0.0f };
+
+    float frac;
+    int32_t exp;
+    int i;
+    for ( i = 0; i < 12; i++ ) {
+        stdlib_base_frexpf( x[i], &frac, &exp );
+        printf( "x: %f => frac: %f, exp: %" PRId32 "\n", x[i], frac, exp );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
+
+[@stdlib/math/base/special/absf]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/math/base/special/absf
+
+<!-- <related-links> -->
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/math/base/special/frexpf/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var uniform = require( '@stdlib/random/array/uniform' );
+var isArray = require( '@stdlib/assert/is-array' );
+var pkg = require( './../package.json' ).name;
+var frexpf = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var x;
+	var y;
+	var i;
+
+	x = uniform( 100, -5.0e6, 5.0e6, {
+		'dtype': 'float32'
+	});
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = frexpf( x[ i%x.length ] );
+		if ( typeof y !== 'object' ) {
+			b.fail( 'should return an array' );
+		}
+	}
+	b.toc();
+	if ( !isArray( y ) ) {
+		b.fail( 'should return an array' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+':assign', function benchmark( b ) {
+	var out;
+	var x;
+	var y;
+	var i;
+
+	out = [ 0.0, 0.0 ];
+	x = uniform( 100, -5.0e6, 5.0e6, {
+		'dtype': 'float32'
+	});
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		y = frexpf.assign( x[ i%x.length ], out, 1, 0 );
+		if ( typeof out !== 'object' ) {
+			b.fail( 'should return an array' );
+		}
+	}
+	b.toc();
+	if ( !isArray( y ) || y !== out ) {
+		b.fail( 'should return the output array' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});