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feat: add blas/ext/base/sindex-of
PR-URL: #7318 Ref: #2656 Co-authored-by: Athan Reines <[email protected]> Reviewed-by: Athan Reines <[email protected]>
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<!--
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@license Apache-2.0
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Copyright (c) 2025 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# sindexOf
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> Return the first index of a specified search element in a single-precision floating-point strided array.
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- Package usage documentation. -->
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<section class="usage">
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## Usage
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```javascript
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var sindexOf = require( '@stdlib/blas/ext/base/sindex-of' );
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```
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#### sindexOf( N, searchElement, x, strideX )
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Returns the first index of a specified search element in a single-precision floating-point strided array.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, 3.0 ] );
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var idx = sindexOf( x.length, 3.0, x, 1 );
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// returns 2
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```
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The function has the following parameters:
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- **N**: number of indexed elements.
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- **searchElement**: search element.
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- **x**: input [`Float32Array`][@stdlib/array/float32].
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- **strideX**: stride length.
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If the function is unable to find a search element, the function returns `-1`.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, 3.0 ] );
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var idx = sindexOf( x.length, 8.0, x, 1 );
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// returns -1
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```
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The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to search every other element:
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, 3.0 ] );
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var idx = sindexOf( 4, -1.0, x, 2 );
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// returns 3
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```
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Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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// Initial array...
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var x0 = new Float32Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );
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// Create an offset view...
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var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
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// Find index...
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var idx = sindexOf( 3, -6.0, x1, 2 );
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// returns 2
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```
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#### sindexOf.ndarray( N, searchElement, x, strideX, offsetX )
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Returns the first index of a specified search element in a single-precision floating-point strided array using alternative indexing semantics.
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, 3.0 ] );
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var idx = sindexOf.ndarray( x.length, 3.0, x, 1, 0 );
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// returns 2
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```
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The function has the following additional parameters:
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- **offsetX**: starting index.
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While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to access only the last three elements of the strided array
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```javascript
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var Float32Array = require( '@stdlib/array/float32' );
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var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, 3.0 ] );
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var idx = sindexOf.ndarray( 3, 3.0, x, 1, x.length-3 );
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// returns 2
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```
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</section>
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<!-- /.usage -->
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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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## Notes
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- When searching for a search element, the function checks for equality using the strict equality operator `===`. As a consequence, `NaN` values are considered distinct, and `-0` and `+0` are considered the same.
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</section>
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<!-- /.notes -->
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<!-- Package usage examples. -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
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var sindexOf = require( '@stdlib/blas/ext/base/sindex-of' );
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var x = discreteUniform( 10, -100, 100, {
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'dtype': 'float32'
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});
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console.log( x );
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var idx = sindexOf( x.length, 80.0, x, 1 );
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console.log( idx );
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```
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</section>
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<!-- /.examples -->
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<!-- C interface documentation. -->
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* * *
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<section class="c">
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## C APIs
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- C usage documentation. -->
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<section class="usage">
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### Usage
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```c
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#include "stdlib/blas/ext/base/sindex_of.h"
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```
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#### stdlib_strided_sindex_of( N, searchElement, \*X, strideX )
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Returns the first index of a specified search element in a single-precision floating-point strided array.
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```c
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float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
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int idx = stdlib_strided_sindex_of( 4, 3.0f, x, 1 );
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// returns 2
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```
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The function accepts the following arguments:
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- **N**: `[in] CBLAS_INT` number of indexed elements.
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- **searchElement**: `[in] float` search element.
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- **X**: `[in] float*` input array.
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- **strideX**: `[in] CBLAS_INT` stride length.
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```c
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CBLAS_INT N stdlib_strided_sindex_of( const CBLAS_INT N, const float searchElement, float *X, const CBLAS_INT strideX );
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```
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#### stdlib_strided_sindex_of_ndarray( N, searchElement, \*X, strideX, offsetX )
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Returns the first index of a specified search element in a single-precision floating-point strided array using alternative indexing semantics.
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```c
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float x[] = { 1.0f, 2.0f, 3.0f, 4.0f };
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int idx = stdlib_strided_sindex_of( 4, 3.0f, x, 1, 0 );
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// returns 2
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```
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The function accepts the following arguments:
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- **N**: `[in] CBLAS_INT` number of indexed elements.
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- **searchElement**: `[in] float` search element.
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- **X**: `[in] float*` input array.
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- **strideX**: `[in] CBLAS_INT` stride length.
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- **offsetX**: `[in] CBLAS_INT` starting index.
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```c
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CBLAS_INT stdlib_strided_sindex_of_ndarray( const CBLAS_INT N, const float searchElement, float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
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```
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</section>
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<!-- /.usage -->
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<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<!-- C API usage examples. -->
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<section class="examples">
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### Examples
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```c
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#include "stdlib/blas/ext/base/sindex_of.h"
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#include <stdio.h>
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int main( void ) {
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// Create a strided array:
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float x[] = { 1.0f, -2.0f, 3.0f, -4.0f, 5.0f, -6.0f, 7.0f, -8.0f };
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// Specify the number of indexed elements:
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const int N = 8;
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// Specify a stride:
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const int strideX = 1;
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// Perform a search:
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int idx = stdlib_strided_sindex_of( N, 5.0f, x, strideX );
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// Print the result:
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printf( "index value: %d\n", idx );
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}
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.c -->
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<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="references">
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</section>
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<!-- /.references -->
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<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
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<section class="related">
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</section>
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<!-- /.related -->
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<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="links">
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[@stdlib/array/float32]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float32
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[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
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</section>
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<!-- /.links -->

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