feat: add C ndarray implementation for blas/base/dznrm2

lib/node_modules/@stdlib/blas/base/dznrm2/README.md

@@ -194,6 +194,28 @@ The function accepts the following arguments:
 double c_dznrm2( const CBLAS_INT N, const void *ZX, const CBLAS_INT strideX );
 ```
 
+#### c_dznrm2_ndarray( N, \*ZX, strideX, offsetX )
+
+Computes the L2-norm of a complex double-precision floating-point vector using alternative indexing semantics.
+
+```c
+const double zx[] = { 0.3, 0.1, 0.5, 0.0, 0.0, 0.5, 0.0, 0.2 };
+
+double norm = c_dznrm2_ndarray( 4, (void *)zx, 1, 0 );
+// returns 0.8
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **ZX**: `[in] void*` input array.
+-   **strideX**: `[in] CBLAS_INT` index increment for `ZX`.
+-   **offsetX**: `[in] CBLAS_INT` starting index for `ZX`.
+
+```c
+double c_dznrm2_ndarray( const CBLAS_INT N, const void *ZX, const CBLAS_INT strideX, const CBLAS_INT offsetX );
+```
+
 </section>
 
 <!-- /.usage -->
@@ -227,7 +249,13 @@ int main( void ) {
     const int strideX = 1;
 
     // Compute the L2-norm:
-    c_dznrm2( N, (void *)zx, strideX );
+    double norm = c_dznrm2( N, (void *)zx, strideX );
+
+    // Print the result:
+    printf( "L2-norm: %lf\n", norm );
+
+    // Compute the L2-norm using alternative indexing semantics:
+    norm = c_dznrm2_ndarray( N, (void *)zx, -strideX, N-1 );
 
     // Print the result:
     printf( "L2-norm: %lf\n", norm );

lib/node_modules/@stdlib/blas/base/dznrm2/benchmark/c/benchmark.length.c

@@ -94,7 +94,7 @@ static double rand_double( void ) {
 * @param len          array length
 * @return elapsed time in seconds
 */
-static double benchmark( int iterations, int len ) {
+static double benchmark1( int iterations, int len ) {
 	double zx[ len*2 ];
 	double elapsed;
 	double norm;
@@ -121,6 +121,40 @@ static double benchmark( int iterations, int len ) {
 	return elapsed;
 }
 
+/**
+* Runs a benchmark.
+*
+* @param iterations   number of iterations
+* @param len          array length
+* @return elapsed time in seconds
+*/
+static double benchmark2( int iterations, int len ) {
+	double zx[ len*2 ];
+	double elapsed;
+	double norm;
+	double t;
+	int i;
+
+	for ( i = 0; i < len*2; i += 2 ) {
+		zx[ i ] = ( rand_double()*10000.0 ) - 5000.0;
+		zx[ i+1 ] = ( rand_double()*10000.0 ) - 5000.0;
+	}
+	norm = 0.0;
+	t = tic();
+	for ( i = 0; i < iterations; i++ ) {
+		norm = c_dznrm2_ndarray( len, (void *)zx, 1, 0 );
+		if ( norm != norm ) {
+			printf( "should not return NaN\n" );
+			break;
+		}
+	}
+	elapsed = tic() - t;
+	if ( norm != norm ) {
+		printf( "should not return NaN\n" );
+	}
+	return elapsed;
+}
+
 /**
 * Main execution sequence.
 */
@@ -143,7 +177,14 @@ int main( void ) {
 		for ( j = 0; j < REPEATS; j++ ) {
 			count += 1;
 			printf( "# c::%s:len=%d\n", NAME, len );
-			elapsed = benchmark( iter, len );
+			elapsed = benchmark1( iter, len );
+			print_results( iter, elapsed );
+			printf( "ok %d benchmark finished\n", count );
+		}
+		for ( j = 0; j < REPEATS; j++ ) {
+			count += 1;
+			printf( "# c::%s:ndarray:len=%d\n", NAME, len );
+			elapsed = benchmark2( iter, len );
 			print_results( iter, elapsed );
 			printf( "ok %d benchmark finished\n", count );
 		}

lib/node_modules/@stdlib/blas/base/dznrm2/examples/c/example.c

@@ -34,4 +34,10 @@ int main( void ) {
 
 	// Print the result:
 	printf( "L2-norm: %lf\n", norm );
+
+	// Compute the L2-norm using alternative indexing semantics:
+	norm = c_dznrm2_ndarray( N, (void *)zx, -strideX, N-1 );
+
+	// Print the result:
+	printf( "L2-norm: %lf\n", norm );
 }

lib/node_modules/@stdlib/blas/base/dznrm2/include/stdlib/blas/base/dznrm2.h

@@ -36,6 +36,11 @@ extern "C" {
 */
 double API_SUFFIX(c_dznrm2)( const CBLAS_INT N, const void *ZX, const CBLAS_INT strideX );
 
+/**
+* Computes the L2-norm of a complex double-precision floating-point vector using alternative indexing semantics.
+*/
+double API_SUFFIX(c_dznrm2_ndarray)( const CBLAS_INT N, const void *ZX, const CBLAS_INT strideX, const CBLAS_INT offsetX );
+
 #ifdef __cplusplus
 }
 #endif

lib/node_modules/@stdlib/blas/base/dznrm2/lib/ndarray.native.js

@@ -21,7 +21,6 @@
 // MODULES //
 
 var reinterpret = require( '@stdlib/strided/base/reinterpret-complex128' );
-var minViewBufferIndex = require( '@stdlib/strided/base/min-view-buffer-index' );
 var addon = require( './../src/addon.node' );
 
 
@@ -46,10 +45,8 @@ var addon = require( './../src/addon.node' );
 * // returns ~0.8
 */
 function dznrm2( N, zx, strideX, offsetX ) {
-	var viewZX;
-	offsetX = minViewBufferIndex( N, strideX, offsetX );
-	viewZX = reinterpret( zx, offsetX );
-	return addon( N, viewZX, strideX );
+	var viewZX = reinterpret( zx, 0 );
+	return addon.ndarray( N, viewZX, strideX, offsetX );
 }