feat: add blas/base/zscal

lib/node_modules/@stdlib/blas/base/zscal/README.md

@@ -0,0 +1,346 @@
+<!--
+
+@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.
+
+-->
+
+# zscal
+
+> Scales a double-precision complex floating-point vector by a double-precision complex floating-point constant.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var zscal = require( '@stdlib/blas/base/zscal' );
+```
+
+#### zscal( N, za, zx, strideX )
+
+Scales values from `zx` by `za`.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var real = require( '@stdlib/complex/real' );
+var imag = require( '@stdlib/complex/imag' );
+
+var zx = new Complex128Array( [ 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 ] );
+var za = new Complex128( 2.0, 0.0 );
+
+zscal( 3, za, zx, 1 );
+
+var z = zx.get( 0 );
+// returns <Complex128>
+
+var re = real( z );
+// returns 2.0
+
+var im = imag( z );
+// returns 2.0
+```
+
+The function has the following parameters:
+
+-   **N**: number of indexed elements.
+-   **za**: scalar [`Complex128`][@stdlib/complex/float64/ctor] constant. 
+-   **zx**: input [`Complex128Array`][@stdlib/array/complex128].
+-   **strideX**: index increment for `zx`.
+
+The `N` and stride parameters determine how values from `zx` are scaled by `za`. For example, to scale every other value in `zx` by `za`,
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var real = require( '@stdlib/complex/real' );
+var imag = require( '@stdlib/complex/imag' );
+
+var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var za = new Complex128( 2.0, 0.0 );
+
+zscal( 2, za, zx, 2 );
+
+var z = zx.get( 2 );
+// returns <Complex128>
+
+var re = real( z );
+// returns 10.0
+
+var im = imag( 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 Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var real = require( '@stdlib/complex/real' );
+var imag = require( '@stdlib/complex/imag' );
+
+// Initial array:
+var zx0 = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+
+// Define a scalar constant:
+var za = new Complex128( 2.0, 2.0 );
+
+// Create an offset view:
+var zx1 = new Complex128Array( zx0.buffer, zx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
+
+// Scales every other value from `zx1` by `za`...
+zscal( 3, za, zx1, 1 );
+
+var z = zx0.get( 1 );
+// returns <Complex128>
+
+var re = real( z );
+// returns -2.0
+
+var im = imag( z );
+// returns 14.0
+```
+
+#### zscal.ndarray( N, za, zx, strideX, offsetX )
+
+Scales values from `zx` by `za` using alternative indexing semantics.
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var real = require( '@stdlib/complex/real' );
+var imag = require( '@stdlib/complex/imag' );
+
+var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
+var za = new Complex128( 2.0, 2.0 );
+
+zscal.ndarray( 3, za, zx, 1, 0 );
+
+var z = zx.get( 0 );
+// returns <Complex128>
+
+var re = real( z );
+// returns -2.0
+
+var im = imag( z );
+// returns 6.0
+```
+
+The function has the following additional parameters:
+
+-   **offsetX**: starting index for `zx`.
+
+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 scale every other value in the input strided array starting from the second element,
+
+```javascript
+var Complex128Array = require( '@stdlib/array/complex128' );
+var Complex128 = require( '@stdlib/complex/float64/ctor' );
+var real = require( '@stdlib/complex/real' );
+var imag = require( '@stdlib/complex/imag' );
+
+var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
+var za = new Complex128( 2.0, 2.0 );
+
+zscal.ndarray( 2, za, zx, 2, 1 );
+
+var z = zx.get( 3 );
+// returns <Complex128>
+
+var re = real( z );
+// returns -2.0
+
+var im = imag( z );
+// returns 30.0
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If `N <= 0` or `strideX <= 0` , both functions return `zx` unchanged.
+-   `zscal()` corresponds to the [BLAS][blas] level 1 function [`zscal`][zscal].
+
+</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 zscal = require( '@stdlib/blas/base/zscal' );
+
+function rand() {
+    return new Complex128( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
+}
+
+var zx = filledarrayBy( 10, 'complex128', rand );
+console.log( zx.toString() );
+
+var za = new Complex128( 2.0, 2.0 );
+console.log( za.toString() );
+
+// Scales elements from `zx` by `za`:
+zscal( zx.length, za, zx, 1 );
+console.log( zx.get( zx.length-1 ).toString() );
+```
+
+</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/blas/base/zscal.h"
+```
+
+#### c_zscal( N, za, \*ZX, strideX )
+
+Scales values from `ZX` by `za`.
+
+```c
+#include "stdlib/complex/float64/ctor.h"
+
+double zx[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+const stdlib_complex128_t za = stdlib_complex128( 2.0, 2.0 );
+
+c_zscal( 4, za, (void *)zx, 1 );
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **za**: `[in] stdlib_complex128_t` scalar constant.
+-   **ZX**: `[inout] void*` input array.
+-   **strideX**: `[in] CBLAS_INT` index increment for `ZX`.
+
+```c
+void c_zscal( const CBLAS_INT N, const stdlib_complex128_t za, void *ZX, const CBLAS_INT strideX );
+```
+
+</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/blas/base/zscal.h"
+#include "stdlib/complex/float64/ctor.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create a strided array of interleaved real and imaginary components:
+    double zx[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+
+    // Create a complex scalar:
+    const stdlib_complex128_t ca = stdlib_complex128( 2.0, 2.0 );
+
+    // Specify the number of elements:
+    const int N = 4;
+
+    // Specify stride length:
+    const int strideX = 1;
+
+    // Scale the elements of the array:
+    c_zscal( N, za, (void *)zx, strideX );
+
+    // Print the result:
+    for ( int i = 0; i < N; i++ ) {
+        printf( "zx[ %i ] = %f + %fj\n", i, zx[ i*2 ], zx[ (i*2)+1 ] );
+    }
+}
+```
+
+</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">
+
+[blas]: http://www.netlib.org/blas
+
+[zscal]: https://netlib.org/lapack/explore-html-3.6.1/d2/df9/group__complex16__blas__level1_gaceea1208dcd46b6e5468fbfb53b9281b.html
+
+[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
+
+[@stdlib/array/complex128]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/complex128
+
+[@stdlib/complex/float64/ctor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/complex/float64/ctor
+
+</section>
+
+<!-- /.links -->