test: add accessor array tests

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---

Author: gururaj1512

lib/node_modules/@stdlib/stats/base/stdevpn/test/test.ndarray.js

@@ -21,9 +21,9 @@
 // MODULES //
 
 var tape = require( 'tape' );
-var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var toAccessorArray = require( '@stdlib/array/base/to-accessor-array' );
 var stdevpn = require( './../lib/ndarray.js' );
 
 
@@ -44,6 +44,25 @@ tape( 'the function calculates the population standard deviation of a strided ar
 	var x;
 	var v;
 
+	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0 ];
+	v = stdevpn( x.length, 0, x, 1, 0 );
+	t.strictEqual( v, sqrt( 53.5/x.length ), 'returns expected value' );
+
+	x = [ -4.0, -4.0 ];
+	v = stdevpn( x.length, 0, x, 1, 0 );
+	t.strictEqual( v, 0.0, 'returns expected value' );
+
+	x = [ NaN, 4.0 ];
+	v = stdevpn( x.length, 0, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function calculates the population standard deviation of a strided array (accessors)', function test( t ) {
+	var x;
+	var v;
+
 	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0 ];
 	v = stdevpn( x.length, 0, toAccessorArray( x ), 1, 0 );
 	t.strictEqual( v, sqrt( 53.5/x.length ), 'returns expected value' );
@@ -63,6 +82,25 @@ tape( 'the function calculates the sample standard deviation of a strided array'
 	var x;
 	var v;
 
+	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0 ];
+	v = stdevpn( x.length, 1, x, 1, 0 );
+	t.strictEqual( v, sqrt( 53.5/(x.length-1) ), 'returns expected value' );
+
+	x = [ -4.0, -4.0 ];
+	v = stdevpn( x.length, 1, x, 1, 0 );
+	t.strictEqual( v, 0.0, 'returns expected value' );
+
+	x = [ NaN, 4.0 ];
+	v = stdevpn( x.length, 1, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function calculates the sample standard deviation of a strided array (accessors)', function test( t ) {
+	var x;
+	var v;
+
 	x = [ 1.0, -2.0, -4.0, 5.0, 0.0, 3.0 ];
 	v = stdevpn( x.length, 1, toAccessorArray( x ), 1, 0 );
 	t.strictEqual( v, sqrt( 53.5/(x.length-1) ), 'returns expected value' );
@@ -84,6 +122,21 @@ tape( 'if provided an `N` parameter less than or equal to `0`, the function retu
 
 	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
 
+	v = stdevpn( 0, 1, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	v = stdevpn( -1, 1, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided an `N` parameter less than or equal to `0`, the function returns `NaN` (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
+
 	v = stdevpn( 0, 1, toAccessorArray( x ), 1, 0 );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
@@ -99,6 +152,18 @@ tape( 'if provided an `N` parameter equal to `1`, the function returns a populat
 
 	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
 
+	v = stdevpn( 1, 0, x, 1, 0 );
+	t.strictEqual( v, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided an `N` parameter equal to `1`, the function returns a population standard deviation of `0` (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
+
 	v = stdevpn( 1, 0, toAccessorArray( x ), 1, 0 );
 	t.strictEqual( v, 0.0, 'returns expected value' );
 
@@ -111,6 +176,21 @@ tape( 'if provided a `correction` parameter yielding `N-correction` less than or
 
 	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
 
+	v = stdevpn( x.length, x.length, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	v = stdevpn( x.length, x.length+1, x, 1, 0 );
+	t.strictEqual( isnan( v ), true, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a `correction` parameter yielding `N-correction` less than or equal to `0`, the function returns `NaN` (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
+
 	v = stdevpn( x.length, x.length, toAccessorArray( x ), 1, 0 );
 	t.strictEqual( isnan( v ), true, 'returns expected value' );
 
@@ -135,6 +215,27 @@ tape( 'the function supports a `stride` parameter', function test( t ) {
 		2.0
 	];
 
+	v = stdevpn( 4, 1, x, 2, 0 );
+
+	t.strictEqual( v, 2.5, 'returns expected value' );
+	t.end();
+});
+
+tape( 'the function supports a `stride` parameter (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		1.0,  // 0
+		2.0,
+		2.0,  // 1
+		-7.0,
+		-2.0, // 2
+		3.0,
+		4.0,  // 3
+		2.0
+	];
+
 	v = stdevpn( 4, 1, toAccessorArray( x ), 2, 0 );
 
 	t.strictEqual( v, 2.5, 'returns expected value' );
@@ -156,6 +257,27 @@ tape( 'the function supports a negative `stride` parameter', function test( t )
 		2.0
 	];
 
+	v = stdevpn( 4, 1, x, -2, 6 );
+
+	t.strictEqual( v, 2.5, 'returns expected value' );
+	t.end();
+});
+
+tape( 'the function supports a negative `stride` parameter (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		1.0,  // 3
+		2.0,
+		2.0,  // 2
+		-7.0,
+		-2.0, // 1
+		3.0,
+		4.0,  // 0
+		2.0
+	];
+
 	v = stdevpn( 4, 1, toAccessorArray( x ), -2, 6 );
 
 	t.strictEqual( v, 2.5, 'returns expected value' );
@@ -168,6 +290,18 @@ tape( 'if provided a `stride` parameter equal to `0`, the function returns `0`',
 
 	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
 
+	v = stdevpn( x.length, 1, x, 0, 0 );
+	t.strictEqual( v, 0.0, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'if provided a `stride` parameter equal to `0`, the function returns `0` (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [ 1.0, -2.0, -4.0, 5.0, 3.0 ];
+
 	v = stdevpn( x.length, 1, toAccessorArray( x ), 0, 0 );
 	t.strictEqual( v, 0.0, 'returns expected value' );
 
@@ -189,6 +323,27 @@ tape( 'the function supports an `offset` parameter', function test( t ) {
 		4.0   // 3
 	];
 
+	v = stdevpn( 4, 1, x, 2, 1 );
+	t.strictEqual( v, 2.5, 'returns expected value' );
+
+	t.end();
+});
+
+tape( 'the function supports an `offset` parameter (accessors)', function test( t ) {
+	var x;
+	var v;
+
+	x = [
+		2.0,
+		1.0,  // 0
+		2.0,
+		-2.0, // 1
+		-2.0,
+		2.0,  // 2
+		3.0,
+		4.0   // 3
+	];
+
 	v = stdevpn( 4, 1, toAccessorArray( x ), 2, 1 );
 	t.strictEqual( v, 2.5, 'returns expected value' );