feat: update JavaScript implementation and add C ndarray implementa…

…tion for `blas/base/idamax`

PR-URL: #2980
Ref: #2039
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com> 
Signed-off-by: Athan Reines <kgryte@gmail.com>

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

@@ -143,6 +143,130 @@ console.log( idx );
 
 <!-- /.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/idamax.h"
+```
+
+#### c_idamax( N, \*X, strideX )
+
+Finds the index of the first element having the maximum absolute value.
+
+```c
+const double x[] = { 4.0, 2.0, -3.0, 5.0, -1.0 };
+
+int idx = c_idamax( 5, x, 1 );
+// returns 3
+```
+
+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`.
+
+```c
+CBLAS_INT c_idamax( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
+```
+
+#### c_idamax_ndarray( N, \*X, strideX, offsetX )
+
+Finds the index of the first element having the maximum absolute value using alternative indexing semantics.
+
+```c
+const double x[] = { 4.0, 2.0, -3.0, 5.0, -1.0 };
+
+int idx = c_idamax_ndarray( 5, x, 1, 0 );
+// returns 3
+```
+
+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`.
+-   **offsetX**: `[in] CBLAS_INT` starting index for `X`.
+
+```c
+CBLAS_INT c_idamax_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/blas/base/idamax.h"
+#include <stdio.h>
+
+int main( void ) {
+    // Create 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 element:
+    const int N = 8;
+
+    // Specify stride:
+    const int strideX = 1;
+
+    // Compute the index of the maximum absolute value:
+    int idx = c_idamax( N, x, strideX );
+
+    // Print the result:
+    printf( "index value: %d\n", idx );
+
+    // Compute the index of the maximum absolute value:
+    idx = c_idamax_ndarray( N, x, -strideX, N-1 );
+
+    // Print the result:
+    printf( "index value: %d\n", idx );
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
+
 <!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
 
 <section class="related">

lib/node_modules/@stdlib/blas/base/idamax/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 t;
@@ -120,6 +120,39 @@ 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 t;
+	int idx;
+	int i;
+
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = ( rand_double()*20000.0 ) - 10000.0;
+	}
+	idx = -1;
+	t = tic();
+	for ( i = 0; i < iterations; i++ ) {
+		idx = c_idamax_ndarray( len, x, 1, 0 );
+		if ( idx < -2 ) {
+			printf( "unexpected result\n" );
+			break;
+		}
+	}
+	elapsed = tic() - t;
+	if ( idx < -2 ) {
+		printf( "unexpected result\n" );
+	}
+	return elapsed;
+}
+
 /**
 * Main execution sequence.
 */
@@ -142,7 +175,14 @@ 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/idamax/examples/c/example.c

@@ -34,4 +34,10 @@ int main( void ) {
 
 	// Print the result:
 	printf( "index value: %d\n", idx );
+
+	// Compute the index of the maximum absolute value:
+	idx = c_idamax_ndarray( N, x, -strideX, N-1 );
+
+	// Print the result:
+	printf( "index value: %d\n", idx );
 }

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

@@ -22,6 +22,8 @@
 #ifndef IDAMAX_H
 #define IDAMAX_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.
 */
@@ -32,7 +34,12 @@ extern "C" {
 /**
 * Finds the index of the first element having the maximum absolute value.
 */
-int c_idamax( const int N, const double *X, const int strideX );
+CBLAS_INT API_SUFFIX(c_idamax)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
+
+/**
+* Finds the index of the first element having the maximum absolute value using alternative indexing semantics.
+*/
+CBLAS_INT API_SUFFIX(c_idamax_ndarray)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
 
 #ifdef __cplusplus
 }

lib/node_modules/@stdlib/blas/base/idamax/include/stdlib/blas/base/idamax_cblas.h

@@ -22,6 +22,8 @@
 #ifndef IDAMAX_CLBAS_H
 #define IDAMAX_CBLAS_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.
 */
@@ -32,7 +34,7 @@ extern "C" {
 /**
 * Finds the index of the first element having the maximum absolute value.
 */
-int cblas_idamax( const int N, const double *X, const int strideX );
+CBLAS_INT API_SUFFIX(cblas_idamax)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX );
 
 #ifdef __cplusplus
 }

lib/node_modules/@stdlib/blas/base/idamax/lib/idamax.js

@@ -20,7 +20,8 @@
 
 // MODULES //
 
-var abs = require( '@stdlib/math/base/special/abs' );
+var stride2offset = require( '@stdlib/strided/base/stride2offset' );
+var ndarray = require( './ndarray.js' );
 
 
 // MAIN //
@@ -42,43 +43,8 @@ var abs = require( '@stdlib/math/base/special/abs' );
 * // returns 4
 */
 function idamax( N, x, strideX ) {
-	var dmax;
-	var idx;
-	var ix;
-	var v;
-	var i;
-
-	if ( N < 1 || strideX <= 0 ) {
-		return -1;
-	}
-	idx = 0;
-	if ( N === 1 ) {
-		return idx;
-	}
-	if (strideX === 1 ) {
-		// Code for stride equal to `1`...
-		dmax = abs( x[ 0 ] );
-		for ( i = 1; i < N; i++ ) {
-			v = abs( x[ i ] );
-			if ( v > dmax ) {
-				idx = i;
-				dmax = v;
-			}
-		}
-		return idx;
-	}
-	// Code for stride not equal to `1`...
-	dmax = abs( x[ 0 ] );
-	ix = strideX;
-	for ( i = 1; i < N; i++ ) {
-		v = abs( x[ ix ] );
-		if ( v > dmax ) {
-			idx = i;
-			dmax = v;
-		}
-		ix += strideX;
-	}
-	return idx;
+	var ox = stride2offset( N, strideX );
+	return ndarray( N, x, strideX, ox );
 }
 
 

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

@@ -20,9 +20,7 @@
 
 // MODULES //
 
-var minViewBufferIndex = require( '@stdlib/strided/base/min-view-buffer-index' );
-var offsetView = require( '@stdlib/strided/base/offset-view' );
-var addon = require( './idamax.native.js' );
+var addon = require( './../src/addon.node' );
 
 
 // MAIN //
@@ -45,13 +43,7 @@ var addon = require( './idamax.native.js' );
 * // returns 3
 */
 function idamax( N, x, strideX, offsetX ) {
-	var viewX;
-	offsetX = minViewBufferIndex( N, strideX, offsetX );
-	viewX = offsetView( x, offsetX );
-	if ( strideX < 0 ) {
-		return N - 1 - addon( N, viewX, -strideX );
-	}
-	return addon( N, viewX, strideX );
+	return addon.ndarray( N, x, strideX, offsetX );
 }