feat: add C ndarray interface and refactor implementation for stats/base/scumaxabs

PR-URL: stdlib-js#4684

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

Author: aayush0325

lib/node_modules/@stdlib/stats/base/scumaxabs/README.md

@@ -54,11 +54,11 @@ The function has the following parameters:
 
 -   **N**: number of indexed elements.
 -   **x**: input [`Float32Array`][@stdlib/array/float32].
--   **strideX**: index increment for `x`.
+-   **strideX**: stride length for `x`.
 -   **y**: output [`Float32Array`][@stdlib/array/float32].
--   **strideY**: index increment for `y`.
+-   **strideY**: stride length for `y`.
 
-The `N` and `stride` parameters determine which elements in `x` and `y` are accessed at runtime. For example, to compute the cumulative maximum absolute value of every other element in `x`,
+The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compute the cumulative maximum absolute value of every other element in `x`,
 
 ```javascript
 var Float32Array = require( '@stdlib/array/float32' );
@@ -108,7 +108,7 @@ 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`, `offsetX` and `offsetY` parameters support indexing semantics based on a starting indices. For example, to calculate the cumulative maximum absolute value of every other value in `x` starting from the second value and to store in the last `N` elements of `y` starting from the last element
+While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, offset parameters support indexing semantics based on a starting indices. For example, to calculate the cumulative maximum absolute value of every other element in `x` starting from the second element and to store in the last `N` elements of `y` starting from the last element
 
 ```javascript
 var Float32Array = require( '@stdlib/array/float32' );
@@ -141,20 +141,14 @@ scumaxabs.ndarray( 4, x, 2, 1, y, -1, y.length-1 );
 <!-- eslint no-undef: "error" -->
 
 ```javascript
-var randu = require( '@stdlib/random/base/randu' );
-var round = require( '@stdlib/math/base/special/round' );
+var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
 var Float32Array = require( '@stdlib/array/float32' );
 var scumaxabs = require( '@stdlib/stats/base/scumaxabs' );
 
-var y;
-var x;
-var i;
-
-x = new Float32Array( 10 );
-y = new Float32Array( x.length );
-for ( i = 0; i < x.length; i++ ) {
-    x[ i ] = round( (randu()*100.0) - 50.0 );
-}
+var x = discreteUniform( 10, -50, 50, {
+    'dtype': 'float32'
+});
+var y = new Float32Array( x.length );
 console.log( x );
 console.log( y );
 
@@ -166,6 +160,93 @@ console.log( y );
 
 <!-- /.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/stats/base/scumaxabs.h"
+```
+
+#### stdlib_strided_scumaxabs( N, \*X, strideX, \*Y, strideY )
+
+Computes the cumulative maximum absolute value of single-precision floating-point strided array elements.
+
+```c
+const float x[] = { 1.0f, 2.0f, -3.0f, 4.0f, -5.0f, 6.0f, 7.0f, 8.0f };
+float y[] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
+
+stdlib_strided_scumaxabs( 4, x, 2, y, -2 );
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **X**: `[in] float*` input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **Y**: `[out] float*` output array.
+-   **strideY**: `[in] CBLAS_INT` stride length for `Y`.
+
+```c
+void stdlib_strided_scumaxabs( const CBLAS_INT N, const float *X, const CBLAS_INT strideX, float *Y, const CBLAS_INT strideY );
+```
+
+#### stdlib_strided_scumaxabs_ndarray(N, \*X, strideX, offsetX, \*Y, strideY, offsetY )
+
+Computes the cumulative maximum absolute value of single-precision floating-point strided array elements using alternative indexing semantics.
+
+```c
+#include "stdlib/stats/base/scumaxabs.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create strided arrays:
+    const float x[] = { 1.0f, 2.0f, -3.0f, 4.0f, -5.0f, 6.0f, 7.0f, 8.0f };
+    const float y[] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
+
+    // Specify the number of elements:
+    const int N = 4;
+
+    // Specify stride lengths:
+    const int strideX = 2;
+    const int strideY = -2;
+
+    // Compute the cumulative maximum absolute value:
+    stdlib_strided_scumaxabs( N, x, strideX, y, strideY );
+
+    // Print the result:
+    for ( int i = 0; i < 8; i++ ) {
+        printf( "y[ %d ] = %f\n", i, y[ i ] );
+    }
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
 <section class="references">
 
 </section>

lib/node_modules/@stdlib/stats/base/scumaxabs/benchmark/benchmark.js

@@ -21,14 +21,21 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var uniform = require( '@stdlib/random/array/uniform' );
 var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var Float32Array = require( '@stdlib/array/float32' );
 var pkg = require( './../package.json' ).name;
 var scumaxabs = require( './../lib/scumaxabs.js' );
 
 
+// VARIABLES //
+
+var options = {
+	'dtype': 'float32'
+};
+
+
 // FUNCTIONS //
 
 /**
@@ -39,15 +46,8 @@ var scumaxabs = require( './../lib/scumaxabs.js' );
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var y;
-	var x;
-	var i;
-
-	x = new Float32Array( len );
-	y = new Float32Array( len );
-	for ( i = 0; i < x.length; i++ ) {
-		x[ i ] = ( randu()*20.0 ) - 10.0;
-	}
+	var x = uniform( len, -10.0, 10.0, options );
+	var y = new Float32Array( len );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/scumaxabs/benchmark/benchmark.native.js

@@ -22,7 +22,7 @@
 
 var resolve = require( 'path' ).resolve;
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var uniform = require( '@stdlib/random/array/uniform' );
 var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var Float32Array = require( '@stdlib/array/float32' );
@@ -36,6 +36,9 @@ var scumaxabs = tryRequire( resolve( __dirname, './../lib/scumaxabs.native.js' )
 var opts = {
 	'skip': ( scumaxabs instanceof Error )
 };
+var options = {
+	'dtype': 'float32'
+};
 
 
 // FUNCTIONS //
@@ -48,15 +51,8 @@ var opts = {
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var x;
-	var y;
-	var i;
-
-	x = new Float32Array( len );
-	y = new Float32Array( len );
-	for ( i = 0; i < x.length; i++ ) {
-		x[ i ] = ( randu()*20.0 ) - 10.0;
-	}
+	var x = uniform( len, -10.0, 10.0, options );
+	var y = new Float32Array( len );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/scumaxabs/benchmark/benchmark.ndarray.js

@@ -21,14 +21,21 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var uniform = require( '@stdlib/random/array/uniform' );
 var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var Float32Array = require( '@stdlib/array/float32' );
 var pkg = require( './../package.json' ).name;
 var scumaxabs = require( './../lib/ndarray.js' );
 
 
+// VARIABLES //
+
+var options = {
+	'dtype': 'float32'
+};
+
+
 // FUNCTIONS //
 
 /**
@@ -39,15 +46,8 @@ var scumaxabs = require( './../lib/ndarray.js' );
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var x;
-	var y;
-	var i;
-
-	x = new Float32Array( len );
-	y = new Float32Array( len );
-	for ( i = 0; i < x.length; i++ ) {
-		x[ i ] = ( randu()*20.0 ) - 10.0;
-	}
+	var x = uniform( len, -10.0, 10.0, options );
+	var y = new Float32Array( len );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/scumaxabs/benchmark/benchmark.ndarray.native.js

@@ -22,7 +22,7 @@
 
 var resolve = require( 'path' ).resolve;
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var uniform = require( '@stdlib/random/array/uniform' );
 var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var Float32Array = require( '@stdlib/array/float32' );
@@ -36,6 +36,9 @@ var scumaxabs = tryRequire( resolve( __dirname, './../lib/ndarray.native.js' ) )
 var opts = {
 	'skip': ( scumaxabs instanceof Error )
 };
+var options = {
+	'dtype': 'float32'
+};
 
 
 // FUNCTIONS //
@@ -48,15 +51,8 @@ var opts = {
 * @returns {Function} benchmark function
 */
 function createBenchmark( len ) {
-	var x;
-	var y;
-	var i;
-
-	x = new Float32Array( len );
-	y = new Float32Array( len );
-	for ( i = 0; i < x.length; i++ ) {
-		x[ i ] = ( randu()*20.0 ) - 10.0;
-	}
+	var x = uniform( len, -10.0, 10.0, options );
+	var y = new Float32Array( len );
 	return benchmark;
 
 	function benchmark( b ) {

lib/node_modules/@stdlib/stats/base/scumaxabs/benchmark/c/benchmark.length.c

@@ -94,7 +94,7 @@ static float rand_float( 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 elapsed;
 	float x[ len ];
 	float y[ len ];
@@ -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 elapsed;
+	float x[ len ];
+	float y[ len ];
+	double t;
+	int i;
+
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = ( rand_float() * 20000.0f ) - 10000.0f;
+		y[ i ] = 0.0f;
+	}
+	t = tic();
+	for ( i = 0; i < iterations; i++ ) {
+		x[ 0 ] += 1.0f;
+		stdlib_strided_scumaxabs_ndarray( len, x, 1, 0, y, 1, 0 );
+		if ( y[ 0 ] != y[ 0 ] ) {
+			printf( "should not return NaN\n" );
+			break;
+		}
+	}
+	elapsed = tic() - t;
+	if ( y[ len-1 ] != y[ len-1 ] ) {
+		printf( "should not return NaN\n" );
+	}
+	return elapsed;
+}
+
 /**
 * Main execution sequence.
 */
@@ -143,7 +177,18 @@ 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 ( i = MIN; i <= MAX; i++ ) {
+		len = pow( 10, i );
+		iter = ITERATIONS / pow( 10, i-1 );
+		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 );
 		}