feat: add C ndarray implementation for stats/base/dmeanpn

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Author: DhruvArvindSingh

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

@@ -51,7 +51,7 @@ The [arithmetic mean][arithmetic-mean] is defined as
 var dmeanpn = require( '@stdlib/stats/base/dmeanpn' );
 ```
 
-#### dmeanpn( N, x, stride )
+#### dmeanpn( N, x, strideX )
 
 Computes the [arithmetic mean][arithmetic-mean] of a double-precision floating-point strided array `x` using a two-pass error correction algorithm.
 
@@ -69,9 +69,9 @@ The function has the following parameters:
 
 -   **N**: number of indexed elements.
 -   **x**: input [`Float64Array`][@stdlib/array/float64].
--   **stride**: index increment for `x`.
+-   **strideX**: index increment for `x`.
 
-The `N` and `stride` parameters determine which elements in `x` are accessed at runtime. For example, to compute the [arithmetic mean][arithmetic-mean] of every other element in `x`,
+The `N` and `strideX` parameters determine which elements in `x` are accessed at runtime. For example, to compute the [arithmetic mean][arithmetic-mean] of every other element in `x`,
 
 ```javascript
 var Float64Array = require( '@stdlib/array/float64' );
@@ -101,7 +101,7 @@ var v = dmeanpn( N, x1, 2 );
 // returns 1.25
 ```
 
-#### dmeanpn.ndarray( N, x, stride, offset )
+#### dmeanpn.ndarray( N, x, stridXe, offset )
 
 Computes the [arithmetic mean][arithmetic-mean] of a double-precision floating-point strided array using a two-pass error correction algorithm and alternative indexing semantics.
 
@@ -175,6 +175,107 @@ console.log( v );
 
 <!-- /.examples -->
 
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/stats/base/dmeanpn.h"
+```
+
+#### stdlib_strided_dmeanpn( N, \*X, strideX )
+
+Computes the [arithmetic mean][arithmetic-mean] of a double-precision floating-point strided array using aa two-pass error correction algorithm.
+
+```c
+const double x[] = { 1.0, -2.0, 2.0 };
+
+double v = stdlib_strided_dmeanpn( x.length, x, 1 );
+// returns ~0.3333
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **X**: `[in] double*` input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+
+```c
+double stdlib_strided_dmeanpn( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
+```
+
+#### stdlib_strided_dmeanpn_ndarray( N, \*X, strideX, offsetX )
+
+Computes the [arithmetic mean][arithmetic-mean] of a double-precision floating-point strided array using a two-pass error correction algorithm and alternative indexing semantics.
+
+```c
+const double x[] = { 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 };
+
+double v = stdlib_strided_dmeankbn2_ndarray( 4, x, 2, 1 );
+// returns 1.25
+```
+
+The function accepts the following arguments:
+
+-   **N**: `[in] CBLAS_INT` number of indexed elements.
+-   **X**: `[in] double*` input array.
+-   **strideX**: `[in] CBLAS_INT` stride length for `X`.
+-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.
+
+```c
+double stdlib_strided_dmeanpn_ndarray( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
+```
+
+</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/stats/base/dmeanpn.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create a strided array:
+    const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
+
+    // Specify the number of elements:
+    const int N = 4;
+
+    // Specify the stride length:
+    const int strideX = 2;
+
+    // Compute the arithmetic mean:
+    double v = stdlib_strided_dmeanpn( N, x, strideX );
+
+    // Print the result:
+    printf( "mean: %lf\n", v );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
 * * *
 
 <section class="references">

lib/node_modules/@stdlib/stats/base/dmeanpn/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 elapsed;
 	double x[ len ];
 	double v;
@@ -107,6 +107,7 @@ static double benchmark( int iterations, int len ) {
 	v = 0.0;
 	t = tic();
 	for ( i = 0; i < iterations; i++ ) {
+		// cppcheck-suppress uninitvar
 		v = stdlib_strided_dmeanpn( len, x, 1 );
 		if ( v != v ) {
 			printf( "should not return NaN\n" );
@@ -120,6 +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;
+	double x[ len ];
+	double v;
+	double t;
+	int i;
+
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = ( rand_double() * 20000.0 ) - 10000.0;
+	}
+	v = 0.0;
+	t = tic();
+	for ( i = 0; i < iterations; i++ ) {
+		// cppcheck-suppress uninitvar
+		v = stdlib_strided_dmeanpn_ndarray( len, x, 1, 0 );
+		if ( v != v ) {
+			printf( "should not return NaN\n" );
+			break;
+		}
+	}
+	elapsed = tic() - t;
+	if ( v != v ) {
+		printf( "should not return NaN\n" );
+	}
+	return elapsed;
+}
+
 /**
 * Main execution sequence.
 */
@@ -142,7 +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 );
 		}

lib/node_modules/@stdlib/stats/base/dmeanpn/include/stdlib/stats/base/dmeanpn.h

@@ -19,7 +19,7 @@
 #ifndef STDLIB_STATS_BASE_DMEANPN_H
 #define STDLIB_STATS_BASE_DMEANPN_H
 
-#include <stdint.h>
+#include "stdlib/blas/base/shared.h"
 
 /*
 * If C++, prevent name mangling so that the compiler emits a binary file having undecorated names, thus mirroring the behavior of a C compiler.
@@ -31,7 +31,13 @@ extern "C" {
 /**
 * Computes the arithmetic mean of a double-precision floating-point strided array using a two-pass error correction algorithm.
 */
-double stdlib_strided_dmeanpn( const int64_t N, const double *X, const int64_t stride );
+double API_SUFFIX( stdlib_strided_dmeanpn )( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
+
+/**
+* Computes the arithmetic mean of a double-precision floating-point strided array using a two-pass error correction algorithm.
+*/
+double API_SUFFIX( stdlib_strided_dmeanpn_ndarray )( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
+
 
 #ifdef __cplusplus
 }

lib/node_modules/@stdlib/stats/base/dmeanpn/lib/dmeanpn.js

@@ -20,8 +20,8 @@
 
 // MODULES //
 
-var dsumpw = require( '@stdlib/blas/ext/base/dsumpw' );
-var dapxsumpw = require( '@stdlib/blas/ext/base/dapxsumpw' );
+var stride2offset = require( '@stdlib/strided/base/stride2offset' );
+var ndarray = require( './ndarray.js' );
 
 
 // MAIN //
@@ -40,7 +40,7 @@ var dapxsumpw = require( '@stdlib/blas/ext/base/dapxsumpw' );
 *
 * @param {PositiveInteger} N - number of indexed elements
 * @param {Float64Array} x - input array
-* @param {integer} stride - stride length
+* @param {integer} strideX - strideX length
 * @returns {number} arithmetic mean
 *
 * @example
@@ -52,23 +52,9 @@ var dapxsumpw = require( '@stdlib/blas/ext/base/dapxsumpw' );
 * var v = dmeanpn( N, x, 1 );
 * // returns ~0.3333
 */
-function dmeanpn( N, x, stride ) {
-	var mu;
-	var c;
-
-	if ( N <= 0 ) {
-		return NaN;
-	}
-	if ( N === 1 || stride === 0 ) {
-		return x[ 0 ];
-	}
-	// Compute an estimate for the mean:
-	mu = dsumpw( N, x, stride ) / N;
-
-	// Compute an error term:
-	c = dapxsumpw( N, -mu, x, stride ) / N;
-
-	return mu + c;
+function dmeanpn( N, x, strideX ) {
+	var ox = stride2offset( N, strideX );
+	return ndarray( N, x, strideX, ox );
 }
 
 

lib/node_modules/@stdlib/stats/base/dmeanpn/lib/dmeanpn.native.js

@@ -30,7 +30,7 @@ var addon = require( './../src/addon.node' );
 *
 * @param {PositiveInteger} N - number of indexed elements
 * @param {Float64Array} x - input array
-* @param {integer} stride - stride length
+* @param {integer} strideX - strideX length
 * @returns {number} arithmetic mean
 *
 * @example
@@ -40,10 +40,10 @@ var addon = require( './../src/addon.node' );
 * var N = x.length;
 *
 * var v = dmeanpn( N, x, 1 );
-* // returns ~0.3333
+*  //returns ~0.3333
 */
-function dmeanpn( N, x, stride ) {
-	return addon( N, x, stride );
+function dmeanpn( N, x, strideX ) {
+	return addon( N, x, strideX );
 }
 
 

lib/node_modules/@stdlib/stats/base/dmeanpn/lib/ndarray.js

@@ -40,7 +40,7 @@ var dapxsumpw = require( '@stdlib/blas/ext/base/dapxsumpw' ).ndarray;
 *
 * @param {PositiveInteger} N - number of indexed elements
 * @param {Float64Array} x - input array
-* @param {integer} stride - stride length
+* @param {integer} strideX - strideX length
 * @param {NonNegativeInteger} offset - starting index
 * @returns {number} arithmetic mean
 *
@@ -54,21 +54,21 @@ var dapxsumpw = require( '@stdlib/blas/ext/base/dapxsumpw' ).ndarray;
 * var v = dmeanpn( N, x, 2, 1 );
 * // returns 1.25
 */
-function dmeanpn( N, x, stride, offset ) {
+function dmeanpn( N, x, strideX, offset ) {
 	var mu;
 	var c;
 
 	if ( N <= 0 ) {
 		return NaN;
 	}
-	if ( N === 1 || stride === 0 ) {
+	if ( N === 1 || strideX === 0 ) {
 		return x[ offset ];
 	}
 	// Compute an estimate for the mean:
-	mu = dsumpw( N, x, stride, offset ) / N;
+	mu = dsumpw( N, x, strideX, offset ) / N;
 
 	// Compute an error term:
-	c = dapxsumpw( N, -mu, x, stride, offset ) / N;
+	c = dapxsumpw( N, -mu, x, strideX, offset ) / N;
 
 	return mu + c;
 }

lib/node_modules/@stdlib/stats/base/dmeanpn/lib/ndarray.native.js

@@ -20,8 +20,7 @@
 
 // MODULES //
 
-var Float64Array = require( '@stdlib/array/float64' );
-var addon = require( './dmeanpn.native.js' );
+var addon = require( './../src/addon.node' );
 
 
 // MAIN //
@@ -31,8 +30,8 @@ var addon = require( './dmeanpn.native.js' );
 *
 * @param {PositiveInteger} N - number of indexed elements
 * @param {Float64Array} x - input array
-* @param {integer} stride - stride length
-* @param {NonNegativeInteger} offset - starting index
+* @param {integer} strideX - stride length
+* @param {NonNegativeInteger} offsetX - starting index
 * @returns {number} arithmetic mean
 *
 * @example
@@ -43,15 +42,10 @@ var addon = require( './dmeanpn.native.js' );
 * var N = floor( x.length / 2 );
 *
 * var v = dmeanpn( N, x, 2, 1 );
-* // returns 1.25
+*  //returns 1.25
 */
-function dmeanpn( N, x, stride, offset ) {
-	var view;
-	if ( stride < 0 ) {
-		offset += (N-1) * stride;
-	}
-	view = new Float64Array( x.buffer, x.byteOffset+(x.BYTES_PER_ELEMENT*offset), x.length-offset ); // eslint-disable-line max-len
-	return addon( N, view, stride );
+function dmeanpn( N, x, strideX, offsetX ) {
+	return addon.ndarray( N, x, strideX, offsetX );
 }