feat: add BLAS Level 1 cscal

lib/node_modules/@stdlib/blas/base/cscal/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.
+
+-->
+
+# cscal
+
+> Scales a complex single-precision floating-point vector by a single-precision floating point constant.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var cscal = require( '@stdlib/blas/base/cscal' );
+```
+
+#### cscal( N, cx, x, strideX )
+
+Scales values from `x` by `cx`.
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+
+var x = new Complex64Array( [ 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 ] );
+var cx = new Complex64Array( [ 2.0, 0.0 ] );
+cscal( 3, cx, x, 1 );
+
+var z = x.get( 0 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns 2.0
+
+var im = imagf( z );
+// returns 2.0
+```
+
+The function has the following parameters:
+
+-   **N**: number of indexed elements.
+-   **cx**: complex constant 
+-   **x**: input [`Complex64Array`][@stdlib/array/complex64].
+-   **strideX**: index increment for `x`.
+
+The `N` and stride parameters determine how values from `x` are scaled by `cx`. For example, to scale every other value in `x` by `cx`,
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+
+var x = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var cx = new Complex64Array( [ 2.0, 0.0 ] );
+
+cscal( 2, cx, x, 2 );
+
+var z = x.get( 2 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns 10.0
+
+var im = imagf( z );
+// returns 12.0
+```
+
+Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
+
+<!-- eslint-disable stdlib/capitalized-comments -->
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+
+// Initial arrays...
+var x0 = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var cx = new Complex64Array( [ 2.0, 2.0 ] );
+
+// Create offset views...
+var x1 = new Complex64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+
+// Copy in reverse order every other value from `x1` into `y1`...
+cscal( 3, cx, x1, 1 );
+
+var z = x0.get( 1 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns -2.0
+
+var im = imagf( z );
+// returns 14.0
+```
+
+#### cscal.ndarray( N, cx, x, strideX, offsetX )
+
+Scales values from `x` by `cx` using alternative indexing semantics.
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+
+var x = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
+var cx = new Complex64Array( [ 2.0, 2.0 ] );
+
+cscal.ndarray( x.length, cx, x, 1, 0 );
+
+var z = x.get( 0 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns -2.0
+
+var im = imagf( z );
+// returns 6.0
+```
+
+The function has the following additional parameters:
+
+-   **offsetX**: starting index for `x`.
+
+While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on starting indices. For example, to scale every other value in `x` starting from the second value by `cx` where `x[i] = cx[0] * x[i]`, `x[i+1] = cx[1] * x[i+1]`,...,
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var realf = require( '@stdlib/complex/realf' );
+var imagf = require( '@stdlib/complex/imagf' );
+
+var x = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var cx = new Complex64Array( [ 2.0, 2.0 ] );
+
+cscal.ndarray( 2, cx, x, 2, 1 );
+
+var z = x.get( 3 );
+// returns <Complex64>
+
+var re = realf( z );
+// returns -2.0
+
+var im = imagf( z );
+// returns 30.0
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If `N <= 0` or `strideX <= 0` , both functions return `x` unchanged.
+-   `cscal()` corresponds to the [BLAS][blas] level 1 function [`cscal`][cscal].
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var Complex64Array = require( '@stdlib/array/complex64' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
+var filledarrayBy = require( '@stdlib/array/filled-by' );
+var Complex64 = require( '@stdlib/complex/float32' );
+var cscal = require( '@stdlib/blas/base/cscal' );
+
+function rand() {
+    return new Complex64( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
+}
+
+var x = filledarrayBy( 10, 'complex64', rand );
+console.log( x.get( 0 ).toString() );
+var cx = new Complex64Array( [ 2.0, 2.0 ] );
+
+// Scales elements from `x` by `cx`:
+cscal( x.length, cx, x, 1 );
+console.log( x.get( x.length-1 ).toString() );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+* * *
+
+## See Also
+
+-   <span class="package-name">[`@stdlib/blas/base/cswap`][@stdlib/blas/base/cswap]</span><span class="delimiter">: </span><span class="description">interchanges two complex single-precision floating-point vectors.</span>
+
+</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">
+
+[blas]: http://www.netlib.org/blas
+
+[cscal]: https://www.netlib.org/lapack/explore-html/d2/de8/group__scal_gacce468103c83fa18bae078d5f49fefe2.html#gacce468103c83fa18bae078d5f49fefe2
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+[@stdlib/array/complex64]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/complex64
+
+<!-- <related-links> -->
+
+[@stdlib/blas/base/cswap]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/blas/base/cswap
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/blas/base/cscal/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 isnan = require( '@stdlib/math/base/assert/is-nan' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var Complex64Array = require( '@stdlib/array/complex64' );
+var reinterpret = require( '@stdlib/strided/base/reinterpret-complex64' );
+var pkg = require( './../package.json' ).name;
+var cscal = require( './../lib/cscal.js' );
+
+
+// VARIABLES //
+
+var options = {
+	'dtype': 'float32'
+};
+
+
+// FUNCTIONS //
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var cx;
+	var x;
+
+	x = uniform( len*2, -100.0, 100.0, options );
+	x = new Complex64Array( x.buffer );
+
+	cx = new Complex64Array( [ 2.0, -2.0 ] );
+
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var viewX;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			cscal( len, cx, x, 1 );
+			viewX = reinterpret( x, 0 );
+			if ( isnan( viewX[ i%(len*2) ] ) ) {
+				b.fail( 'should not return NaN' );
+			}
+		}
+		b.toc();
+		if ( isnan( viewX[ i%(len*2) ] ) ) {
+			b.fail( 'should not return NaN' );
+		}
+		b.pass( 'benchmark finished' );
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+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();