refactor: update stride handling and function documentation for blas/ext/base/dasumpw

PR-URL: #3362

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: headlessNode

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

@@ -59,19 +59,18 @@ Computes the sum of absolute values ([_L1_ norm][l1norm]) of double-precision fl
 var Float64Array = require( '@stdlib/array/float64' );
 
 var x = new Float64Array( [ 1.0, -2.0, 2.0 ] );
-var N = x.length;
 
-var v = dasumpw( N, x, 1 );
+var v = dasumpw( x.length, x, 1 );
 // returns 5.0
 ```
 
 The function has the following parameters:
 
 -   **N**: number of indexed elements.
 -   **x**: input [`Float64Array`][@stdlib/array/float64].
--   **strideX**: index increment for `x`.
+-   **strideX**: stride length for `x`.
 
-The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the sum of absolute values of every other element in `x`,
+The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the sum of absolute values of every other element:
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
@@ -104,17 +103,16 @@ Computes the sum of absolute values ([_L1_ norm][l1norm]) of double-precision fl
 var Float64Array = require( '@stdlib/array/float64' );
 
 var x = new Float64Array( [ 1.0, -2.0, 2.0 ] );
-var N = x.length;
 
-var v = dasumpw.ndarray( N, x, 1, 0 );
+var v = dasumpw.ndarray( x.length, x, 1, 0 );
 // returns 5.0
 ```
 
 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 parameter supports indexing semantics based on a starting index. For example, to calculate the sum of absolute values of every other value in `x` starting from the second value
+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 calculate the sum of absolute values of every other element starting from the second element:
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
@@ -204,7 +202,7 @@ The function accepts the following arguments:
 
 -   **N**: `[in] CBLAS_INT` number of indexed elements.
 -   **X**: `[in] double*` input array.
--   **strideX**: `[in] CBLAS_INT` index increment for `X`.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
 
 ```c
 double stdlib_strided_dasumpw( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
@@ -225,7 +223,7 @@ The function accepts the following arguments:
 
 -   **N**: `[in] CBLAS_INT` number of indexed elements.
 -   **X**: `[in] double*` input array.
--   **strideX**: `[in] CBLAS_INT` index increment for `X`.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
 -   **offsetX**: `[in] CBLAS_INT` starting index for `X`.
 
 ```c

lib/node_modules/@stdlib/blas/ext/base/dasumpw/benchmark/c/benchmark.length.c

@@ -107,6 +107,7 @@ static double benchmark1( int iterations, int len ) {
 	v = 0.0;
 	t = tic();
 	for ( i = 0; i < iterations; i++ ) {
+		// cppcheck-suppress uninitvar
 		v = stdlib_strided_dasumpw( len, x, 1 );
 		if ( v != v ) {
 			printf( "should not return NaN\n" );
@@ -140,6 +141,7 @@ static double benchmark2( int iterations, int len ) {
 	v = 0.0;
 	t = tic();
 	for ( i = 0; i < iterations; i++ ) {
+		// cppcheck-suppress uninitvar
 		v = stdlib_strided_dasumpw_ndarray( len, x, 1, 0 );
 		if ( v != v ) {
 			printf( "should not return NaN\n" );

lib/node_modules/@stdlib/blas/ext/base/dasumpw/docs/repl.txt

@@ -20,7 +20,7 @@
         Input array.
 
     strideX: integer
-        Index increment.
+        Stride length.
 
     Returns
     -------
@@ -34,19 +34,17 @@
     > {{alias}}( x.length, x, 1 )
     5.0
 
-    // Using `N` and `stride` parameters:
+    // Using `N` and stride parameters:
     > x = new {{alias:@stdlib/array/float64}}( [ -2.0, 1.0, 1.0, -5.0, 2.0, -1.0 ] );
-    > var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
     > var stride = 2;
-    > {{alias}}( N, x, stride )
+    > {{alias}}( 3, x, stride )
     5.0
 
     // Using view offsets:
     > var x0 = new {{alias:@stdlib/array/float64}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ] );
     > var x1 = new {{alias:@stdlib/array/float64}}( x0.buffer, x0.BYTES_PER_ELEMENT*1 );
-    > N = {{alias:@stdlib/math/base/special/floor}}( x0.length / 2 );
     > stride = 2;
-    > {{alias}}( N, x1, stride )
+    > {{alias}}( 3, x1, stride )
     5.0
 
 
@@ -68,7 +66,7 @@
         Input array.
 
     strideX: integer
-        Index increment.
+        Stride length.
 
     offsetX: integer
         Starting index.
@@ -87,8 +85,7 @@
 
     // Using offset parameter:
     > var x = new {{alias:@stdlib/array/float64}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0 ] );
-    > var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
-    > {{alias}}.ndarray( N, x, 2, 1 )
+    > {{alias}}.ndarray( 3, x, 2, 1 )
     5.0
 
     See Also

lib/node_modules/@stdlib/blas/ext/base/dasumpw/lib/dasumpw.js

@@ -46,9 +46,8 @@ var ndarray = require( './ndarray.js' );
 * var Float64Array = require( '@stdlib/array/float64' );
 *
 * var x = new Float64Array( [ 1.0, -2.0, 2.0 ] );
-* var N = x.length;
 *
-* var v = dasumpw( N, x, 1 );
+* var v = dasumpw( x.length, x, 1 );
 * // returns 5.0
 */
 function dasumpw( N, x, strideX ) {

lib/node_modules/@stdlib/blas/ext/base/dasumpw/lib/index.js

@@ -28,9 +28,8 @@
 * var dasumpw = require( '@stdlib/blas/ext/base/dasumpw' );
 *
 * var x = new Float64Array( [ 1.0, -2.0, 2.0 ] );
-* var N = x.length;
 *
-* var v = dasumpw( N, x, 1 );
+* var v = dasumpw( x.length, x, 1 );
 * // returns 5.0
 *
 * @example

lib/node_modules/@stdlib/blas/ext/base/dasumpw/lib/ndarray.js

@@ -75,10 +75,10 @@ function dasumpw( N, x, strideX, offsetX ) {
 	if ( N <= 0 ) {
 		return 0.0;
 	}
-	if ( N === 1 || strideX === 0 ) {
-		return abs( x[ offsetX ] );
-	}
 	ix = offsetX;
+	if ( strideX === 0 ) {
+		return N * abs( x[ ix ] );
+	}
 	if ( N < 8 ) {
 		// Use simple summation...
 		s = 0.0;
@@ -113,7 +113,7 @@ function dasumpw( N, x, strideX, offsetX ) {
 			ix += 8 * strideX;
 		}
 		// Pairwise sum the accumulators:
-		s = ((s0+s1) + (s2+s3)) + ((s4+s5) + (s6+s7));
+		s = ( (s0+s1) + (s2+s3) ) + ( (s4+s5) + (s6+s7) );
 
 		// Clean-up loop...
 		for ( i; i < N; i++ ) {

lib/node_modules/@stdlib/blas/ext/base/dasumpw/src/main.c

@@ -55,16 +55,16 @@ double API_SUFFIX(stdlib_strided_dasumpw)( const CBLAS_INT N, const double *X, c
 *
 * @param N        number of indexed elements
 * @param X        input array
-* @param strideX  index increment
+* @param strideX  stride length
 * @param offsetX  starting index
 * @return         output value
 */
 double API_SUFFIX(stdlib_strided_dasumpw_ndarray)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX ) {
-	double sum;
 	CBLAS_INT ix;
 	CBLAS_INT M;
 	CBLAS_INT n;
 	CBLAS_INT i;
+	double sum;
 	double s0;
 	double s1;
 	double s2;
@@ -77,10 +77,10 @@ double API_SUFFIX(stdlib_strided_dasumpw_ndarray)( const CBLAS_INT N, const doub
 	if ( N <= 0 ) {
 		return 0.0;
 	}
-	if ( N == 1 || strideX == 0 ) {
-		return stdlib_base_abs( X[ 0 ] );
-	}
 	ix = offsetX;
+	if ( strideX == 0 ) {
+		return N * stdlib_base_abs( X[ ix ] );
+	}
 	if ( N < 8 ) {
 		// Use simple summation...
 		sum = 0.0;

lib/node_modules/@stdlib/blas/ext/base/dasumpw/test/test.dasumpw.js

@@ -156,14 +156,14 @@ tape( 'the function supports a negative `stride` parameter', function test( t )
 	t.end();
 });
 
-tape( 'if provided a `stride` parameter equal to `0`, the function returns the first element', function test( t ) {
+tape( 'if provided a `stride` parameter equal to `0`, the function returns the sum of first element repeated N times', function test( t ) {
 	var x;
 	var v;
 
 	x = new Float64Array( [ 1.0, -2.0, -4.0, 5.0, 3.0 ] );
 
 	v = dasumpw( x.length, x, 0 );
-	t.strictEqual( v, 1.0, 'returns expected value' );
+	t.strictEqual( v, 5.0, 'returns expected value' );
 
 	t.end();
 });

lib/node_modules/@stdlib/blas/ext/base/dasumpw/test/test.dasumpw.native.js

@@ -247,14 +247,14 @@ tape( 'the function supports a negative `stride` parameter', opts, function test
 	t.end();
 });
 
-tape( 'if provided a `stride` parameter equal to `0`, the function returns the first element', opts, function test( t ) {
+tape( 'if provided a `stride` parameter equal to `0`, the function returns the sum of first element repeated N times', opts, function test( t ) {
 	var x;
 	var v;
 
 	x = new Float64Array( [ 1.0, -2.0, -4.0, 5.0, 3.0 ] );
 
 	v = dasumpw( x.length, x, 0 );
-	t.strictEqual( v, 1.0, 'returns expected value' );
+	t.strictEqual( v, 5.0, 'returns expected value' );
 
 	t.end();
 });

lib/node_modules/@stdlib/blas/ext/base/dasumpw/test/test.ndarray.js

@@ -156,14 +156,14 @@ tape( 'the function supports a negative `stride` parameter', function test( t )
 	t.end();
 });
 
-tape( 'if provided a `stride` parameter equal to `0`, the function returns the first indexed element', function test( t ) {
+tape( 'if provided a `stride` parameter equal to `0`, the function returns the sum of first element repeated N times', function test( t ) {
 	var x;
 	var v;
 
 	x = new Float64Array( [ 1.0, -2.0, -4.0, 5.0, 3.0 ] );
 
 	v = dasumpw( x.length, x, 0, 0 );
-	t.strictEqual( v, 1.0, 'returns expected value' );
+	t.strictEqual( v, 5.0, 'returns expected value' );
 
 	t.end();
 });