feat: add C implementation for blas/base/zaxpy

PR-URL: #7594
Ref: #2039
Co-authored-by: Athan Reines <[email protected]>
Reviewed-by: Athan Reines <[email protected]> 
Co-authored-by: stdlib-bot <[email protected]>

Author: 3 people

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

@@ -51,11 +51,11 @@ The function has the following parameters:
 -   **N**: number of indexed elements.
 -   **alpha**: scalar [`Complex128`][@stdlib/complex/float64/ctor] constant.
 -   **x**: first input [`Complex128Array`][@stdlib/array/complex128].
--   **strideX**: index increment for `x`.
+-   **strideX**: stride length for `x`.
 -   **y**: second input [`Complex128Array`][@stdlib/array/complex128].
--   **strideY**: index increment for `y`.
+-   **strideY**: stride length for `y`.
 
-The `N` and stride parameters determine how values from `x` are scaled by `alpha` and added to `y`. For example, to scale every other value in `x` by `alpha` and add the result to every other value of `y`,
+The `N` and stride parameters determine how elements from `x` are scaled by `alpha` and added to `y`. For example, to scale every other element in `x` by `alpha` and add the result to every other element of `y`,
 
 ```javascript
 var Complex128Array = require( '@stdlib/array/complex128' );
@@ -88,7 +88,7 @@ var alpha = new Complex128( 2.0, 2.0 );
 var x1 = new Complex128Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
 var y1 = new Complex128Array( y0.buffer, y0.BYTES_PER_ELEMENT*2 ); // start at 3rd element
 
-// Scales values of `x0` by `alpha` starting from second index and add the result to `y0` starting from third index...
+// Perform operation:
 zaxpy( 2, alpha, x1, 1, y1, 1 );
 // y0 => <Complex128Array>[ 1.0, 1.0, 1.0, 1.0, -1.0, 15.0, -1.0, 23.0 ]
 ```
@@ -114,7 +114,7 @@ The function has the following additional parameters:
 -   **offsetX**: starting index for `x`.
 -   **offsetY**: starting index for `y`.
 
-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 values in the first input strided array starting from the second element and add the result to the second input array starting from the second element,
+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 elements in the first input strided array starting from the second element and add the result to the second input array starting from the second element,
 
 ```javascript
 var Complex128Array = require( '@stdlib/array/complex128' );
@@ -136,7 +136,7 @@ zaxpy.ndarray( 3, alpha, x, 1, 1, y, 1, 1 );
 
 ## Notes
 
--   If `N <= 0`, both functions return `y` unchanged.
+-   If `N <= 0` or `alpha == 0`, both functions return `y` unchanged.
 -   `zaxpy()` corresponds to the [BLAS][blas] level 1 function [`zaxpy`][zaxpy].
 
 </section>
@@ -164,21 +164,175 @@ function rand() {
 
 var x = filledarrayBy( 10, 'complex128', rand );
 var y = filledarrayBy( 10, 'complex128', rand );
-var yc = zcopy( y.length, y, 1, zeros( y.length, 'complex128' ), 1 );
+var yc1 = zcopy( y.length, y, 1, zeros( y.length, 'complex128' ), 1 );
 
 var alpha = new Complex128( 2.0, 2.0 );
 
-// Scale values from `x` by `alpha` and add the result to `y`:
-zaxpy( x.length, alpha, x, 1, y, 1 );
+// Perform operation:
+zaxpy( x.length, alpha, x, 1, yc1, 1 );
 
 // Print the results:
-logEach( '(%s)*(%s) + (%s) = %s', alpha, x, yc, y );
+logEach( '(%s)*(%s) + (%s) = %s', alpha, x, y, yc1 );
+
+var yc2 = zcopy( y.length, y, 1, zeros( y.length, 'complex128' ), 1 );
+
+// Perform operation using alternative indexing semantics:
+zaxpy.ndarray( x.length, alpha, x, 1, 0, yc2, 1, 0 );
+
+// Print the results:
+logEach( '(%s)*(%s) + (%s) = %s', alpha, x, y, yc2 );
+```
+
+</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/zaxpy.h"
+```
+
+#### c_zaxpy( N, alpha, \*X, strideX, \*Y, strideY )
+
+Scales values from `X` by `alpha` and adds the result to `Y`.
+
+```c
+#include "stdlib/complex/float64/ctor.h"
+
+const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+double y[] = { -1.0, -2.0, -3.0, -4.0, -5.0, -6.0, -7.0, -8.0 };
+const stdlib_complex128_t alpha = stdlib_complex128( 2.0, 2.0 );
+
+c_zaxpy( 4, alpha, (void *)x, 1, (void *)y, 1 );
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **alpha**: `[in] stdlib_complex128_t` scalar constant.
+-   **X**: `[in] void*` input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **Y**: `[inout] void*` output array.
+-   **strideY**: `[in] CBLAS_INT` stride length for `Y`.
+
+```c
+void c_zaxpy( const CBLAS_INT N, const stdlib_complex128_t alpha, const void *X, const CBLAS_INT strideX, void *Y, const CBLAS_INT strideY );
+```
+
+#### c_zaxpy_ndarray( N, alpha, \*X, strideX, offsetX, \*Y, strideY, offsetY )
+
+Scales values from `X` by `alpha` and adds the result to `Y` using alternative indexing semantics.
+
+```c
+#include "stdlib/complex/float64/ctor.h"
+
+const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+double y[] = { -1.0, -2.0, -3.0, -4.0, -5.0, -6.0, -7.0, -8.0 };
+const stdlib_complex128_t alpha = stdlib_complex128( 2.0, 2.0 );
+
+c_zaxpy_ndarray( 4, alpha, (void *)x, 1, 0, (void *)y, 1, 0 );
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **alpha**: `[in] stdlib_complex128_t` scalar constant.
+-   **X**: `[in] void*` input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.
+-   **Y**: `[inout] void*` output array.
+-   **strideY**: `[in] CBLAS_INT` stride length for `Y`.
+-   **offsetY**: `[in] CBLAS_INT` starting index for `Y`.
+
+```c
+void c_zaxpy_ndarray( const CBLAS_INT N, const stdlib_complex128_t alpha, const void *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, void *Y, const CBLAS_INT strideY, const CBLAS_INT offsetY );
+```
+
+</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/zaxpy.h"
+#include "stdlib/complex/float64/ctor.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create strided arrays:
+    const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+    double y[] = { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 };
+
+    // Create a complex scalar:
+    const stdlib_complex128_t alpha = stdlib_complex128( 2.0, 2.0 );
+
+    // Specify the number of elements:
+    const int N = 4;
+
+    // Specify stride lengths:
+    const int strideX = 1;
+    const int strideY = 1;
+
+    // Perform operation:
+    c_zaxpy( N, alpha, (void *)x, strideX, (void *)y, strideY );
+
+    // Print the result:
+    for ( int i = 0; i < N; i++ ) {
+        printf( "zaxpy[ %i ] = %lf + %lfj\n", i, y[ i*2 ], y[ (i*2)+1 ] );
+    }
+
+    // Perform operation using alternative indexing semantics:
+    c_zaxpy_ndarray( N, alpha, (void *)x, strideX, 0, (void *)y, strideY, 0 );
+
+    // Print the result:
+    for ( int i = 0; i < N; i++ ) {
+        printf( "zaxpy[ %i ] = %lf + %lfj\n", i, y[ i*2 ], y[ (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">
@@ -193,7 +347,7 @@ logEach( '(%s)*(%s) + (%s) = %s', alpha, x, yc, y );
 
 [blas]: http://www.netlib.org/blas
 
-[zaxpy]: https://www.netlib.org/lapack/explore-html/d5/d4b/group__axpy_ga0b7bac1f4d42514074a48f14f5f9caa0.html#ga0b7bac1f4d42514074a48f14f5f9caa0
+[zaxpy]: https://www.netlib.org/lapack/explore-html/d5/d4b/group__axpy_gaf603daa00d5c723d0e409d9b2d011bf4.html
 
 [mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
 

lib/node_modules/@stdlib/blas/base/zaxpy/benchmark/benchmark.js

@@ -44,17 +44,17 @@ var options = {
 * Creates a benchmark function.
 *
 * @private
-* @param {PositiveInteger} len - array length
+* @param {PositiveInteger} N - array length
 * @returns {Function} benchmark function
 */
-function createBenchmark( len ) {
+function createBenchmark( N ) {
 	var viewY;
 	var alpha;
 	var x;
 	var y;
 
-	x = new Complex128Array( uniform( len*2, -100.0, 100.0, options ) );
-	y = new Complex128Array( uniform( len*2, -100.0, 100.0, options ) );
+	x = new Complex128Array( uniform( N*2, -100.0, 100.0, options ) );
+	y = new Complex128Array( uniform( N*2, -100.0, 100.0, options ) );
 
 	viewY = reinterpret( y, 0 );
 
@@ -74,12 +74,12 @@ function createBenchmark( len ) {
 		b.tic();
 		for ( i = 0; i < b.iterations; i++ ) {
 			zaxpy( x.length, alpha, x, 1, y, 1 );
-			if ( isnan( viewY[ i%(len*2) ] ) ) {
+			if ( isnan( viewY[ i%(N*2) ] ) ) {
 				b.fail( 'should not return NaN' );
 			}
 		}
 		b.toc();
-		if ( isnan( viewY[ i%(len*2) ] ) ) {
+		if ( isnan( viewY[ i%(N*2) ] ) ) {
 			b.fail( 'should not return NaN' );
 		}
 		b.pass( 'benchmark finished' );
@@ -96,19 +96,19 @@ function createBenchmark( len ) {
 * @private
 */
 function main() {
-	var len;
 	var min;
 	var max;
+	var N;
 	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 );
+		N = pow( 10, i );
+		f = createBenchmark( N );
+		bench( pkg+':len='+N, f );
 	}
 }