feat: add blas/ext/base/zfill

lib/node_modules/@stdlib/blas/ext/base/zfill/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2024 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.
+
+-->
+
+# zfill
+
+> Fill a double-precision complex floating-point strided array with a specified scalar constant.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var zfill = require( '@stdlib/blas/ext/base/zfill' );
+```
+
+#### zfill( N, alpha, x, stride )
+
+Fills a double-precision complex floating-point strided array `x` with a specified scalar constant `alpha`.
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var realf = require( '@stdlib/complex/float64/real' );
+var imagf = require( '@stdlib/complex/float64/imag' );
+
+var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var x = new Complex128Array( arr );
+
+var alpha = new Complex128( 10.0, 10.0 );
+
+zfill( x.length, alpha, x, 1 );
+
+var y = x.get( 0 );
+// returns <Complex128>
+
+var re = realf( y );
+// returns 10.0
+
+var im = imagf( y );
+// returns 10.0
+```
+
+The function has the following parameters:
+
+-   **N**: number of indexed elements.
+-   **alpha**: scalar constant.
+-   **x**: input [`Complex128Array`][@stdlib/array/complex128].
+-   **stride**: index increment.
+
+The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to fill every other element
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var realf = require( '@stdlib/complex/float64/real' );
+var imagf = require( '@stdlib/complex/float64/imag' );
+
+var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var x = new Complex128Array( arr );
+
+var alpha = new Complex128( 10.0, 10.0 );
+
+zfill( 2, alpha, x, 2 );
+
+var y = x.get( 0 );
+// returns <Complex128>
+
+var re = realf( y );
+// returns 10.0
+
+var im = imagf( y );
+// returns 10.0
+
+y = x.get( 1 );
+// returns <Complex128>
+
+re = realf( y );
+// returns 3.0
+
+im = imagf( y );
+// returns 4.0
+```
+
+Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var realf = require( '@stdlib/complex/float64/real' );
+var imagf = require( '@stdlib/complex/float64/imag' );
+
+// Create the underlying floating-point array
+var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+
+// Initial array:
+var x0 = new Complex128Array( arr );
+
+// Create an offset view:
+var x1 = new Complex128Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+
+// Define a scalar constant:
+var alpha = new Complex128( 10.0, 10.0 );
+
+// Fill every other element:
+zfill( 2, alpha, x1, 2 );
+
+var y = x0.get( 0 );
+// returns <Complex128>
+
+var re = realf( y );
+// returns 1.0
+
+var im = imagf( y );
+// returns 2.0
+
+y = x0.get( 1 );
+// returns <Complex128>
+
+re = realf( y );
+// returns 10.0
+
+im = imagf( y );
+// returns 10.0
+```
+
+#### zfill.ndarray( N, alpha, x, stride, offset )
+
+Fills a double-precision complex floating-point strided array `x` with a specified scalar constant `alpha` using alternative indexing semantics.
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var realf = require( '@stdlib/complex/float64/real' );
+var imagf = require( '@stdlib/complex/float64/imag' );
+
+var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var x = new Complex128Array( arr );
+
+var alpha = new Complex128( 10.0, 10.0 );
+
+zfill.ndarray( x.length, alpha, x, 1, 0 );
+
+var y = x.get( 0 );
+// returns <Complex128>
+
+var re = realf( y );
+// returns 10.0
+
+var im = imagf( y );
+// returns 10.0
+```
+
+The function has the following additional parameters:
+
+-   **offset**: starting index.
+
+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 two elements of the strided array
+
+```javascript
+var Float64Array = require( '@stdlib/array/float64' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var realf = require( '@stdlib/complex/float64/real' );
+var imagf = require( '@stdlib/complex/float64/imag' );
+
+var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
+var x = new Complex128Array( arr );
+
+var alpha = new Complex128( 10.0, 10.0 );
+
+zfill.ndarray( 2, alpha, x, 1, x.length-2 );
+
+var y = x.get( 0 );
+// returns <Complex128>
+
+var re = realf( y );
+// returns 1.0
+
+var im = imagf( y );
+// returns 2.0
+
+y = x.get( 1 );
+// returns <Complex128>
+
+re = realf( y );
+// returns 10.0
+
+im = imagf( y );
+// returns 10.0
+
+y = x.get( 2 );
+// returns <Complex128>
+
+re = realf( y );
+// returns 10.0
+
+im = imagf( y );
+// returns 10.0
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If `N <= 0`, both functions return the strided array unchanged.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
+var filledarrayBy = require( '@stdlib/array/filled-by' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var zfill = require( '@stdlib/blas/ext/base/zfill' );
+
+function rand() {
+    return new Complex128( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
+}
+
+var x = filledarrayBy( 10, 'complex128', rand );
+var alpha = new Complex128( 10.0, 10.0 );
+
+zfill( x.length, alpha, x, 1 );
+console.log( x.get( 0 ).toString() );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- 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">
+
+[@stdlib/array/complex128]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/complex128
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/ext/base/zfill/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 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 isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var pkg = require( './../package.json' ).name;
+var zfill = require( './../lib/zfill.js' );
+
+
+// VARIABLES //
+
+var options = {
+	'dtype': 'float64'
+};
+
+
+// FUNCTIONS //
+
+/**
+* Create a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var xbuf;
+	var z;
+	var x;
+
+	xbuf = uniform( len*2, -100.0, 100.0, options );
+	x = new Complex128Array( xbuf.buffer );
+
+	z = new Complex128( 1.0, 0.0 );
+
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			zfill( x.length, z, x, 1 );
+			if ( isnanf( xbuf[ i%(len*2) ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnanf( xbuf[ i%(len*2) ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+function main() {
+	var len;
+	var min;
+	var max;
+	var f;
+	var i;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		len = pow( 10, i );
+		f = createBenchmark( len );
+		bench( pkg+':len='+len, f );
+	}
+}
+
+main();