fix: correct hypergeometric standard deviation implementation

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Author: anandkaranubc

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/README.md

@@ -184,12 +184,12 @@ double out = stdlib_base_dists_hypergeometric_stdev( 16, 11, 4 );
 
 The function accepts the following arguments:
 
--   **N**: `[in] double` population size.
--   **K**: `[in] double` subpopulation size.
--   **n**: `[in] double` number of draws.
+-   **N**: `[in] int32_t` population size.
+-   **K**: `[in] int32_t` subpopulation size.
+-   **n**: `[in] int32_t` number of draws.
 
 ```c
-double stdlib_base_dists_hypergeometric_stdev( const double N, const double K, const double n );
+double stdlib_base_dists_hypergeometric_stdev( const int32_t N, const int32_t K, const int32_t n );
 ```
 
 </section>
@@ -211,10 +211,11 @@ double stdlib_base_dists_hypergeometric_stdev( const double N, const double K, c
 ### Examples
 
 ```c
-#include "stdlib/math/base/special/round.h"
 #include "stdlib/stats/base/dists/hypergeometric/stdev.h"
-#include <stdio.h>
+#include "stdlib/math/base/special/ceil.h"
 #include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
 
 static double random_uniform( const double min, const double max ) {
     double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
@@ -223,17 +224,17 @@ static double random_uniform( const double min, const double max ) {
 
 int main( void ) {
     double sd;
-    double N;
-    double K;
-    double n;
+    int32_t N;
+    int32_t K;
+    int32_t n;
     int i;
 
     for ( i = 0; i < 10; i++ ) {
-        N = stdlib_base_round( random_uniform( 0.0, 20.0 ) );
-        K = stdlib_base_round( random_uniform( 0.0, N ) );
-        n = stdlib_base_round( random_uniform( 0.0, K ) );
+        N = stdlib_base_ceil( random_uniform( 2.0, 100.0 ) );
+        K = stdlib_base_ceil( random_uniform( 0.0, N ) );
+        n = stdlib_base_ceil( random_uniform( 0.0, N ) );
         sd = stdlib_base_dists_hypergeometric_stdev( N, K, n );
-        printf( "N: %lf, K: %lf, n: %lf, SD(X;N,K,n): %lf\n", N, K, n, sd );
+        printf( "N: %d, K: %d, n: %d, SD(X;N,K,n): %lf\n", N, K, n, sd );
     }
 }
 ```

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/benchmark/benchmark.js

@@ -21,10 +21,8 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var floor = require( '@stdlib/math/base/special/floor' );
-var randu = require( '@stdlib/random/base/randu' );
-var uniform = require( '@stdlib/random/base/uniform' );
-var ceil = require( '@stdlib/math/base/special/ceil' );
+var Float64Array = require( '@stdlib/array/float64' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pkg = require( './../package.json' ).name;
 var stdev = require( './../lib' );
@@ -33,18 +31,26 @@ var stdev = require( './../lib' );
 // MAIN //
 
 bench( pkg, function benchmark( b ) {
+	var len;
 	var N;
 	var K;
 	var n;
 	var y;
 	var i;
 
+	len = 100;
+	N = new Float64Array( len );
+	K = new Float64Array( len );
+	n = new Float64Array( len );
+	for ( i = 0; i < len; i++ ) {
+		N[ i ] = discreteUniform( 2, 100 );
+		n[ i ] = discreteUniform( 0, N[ i ] );
+		K[ i ] = discreteUniform( 0, N[ i ] );
+	}
+
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {
-		N = ceil( uniform( 1.0, 100.0 ) );
-		K = floor( randu()*N );
-		n = floor( randu()*N );
-		y = stdev( N, K, n );
+		y = stdev( N[ i % len ], K[ i % len ], n[ i % len ] );
 		if ( isnan( y ) ) {
 			b.fail( 'should not return NaN' );
 		}

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/benchmark/benchmark.native.js

@@ -23,11 +23,9 @@
 var resolve = require( 'path' ).resolve;
 var bench = require( '@stdlib/bench' );
 var Float64Array = require( '@stdlib/array/float64' );
-var randu = require( '@stdlib/random/base/randu' );
-var uniform = require( '@stdlib/random/base/uniform' );
+var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var tryRequire = require( '@stdlib/utils/try-require' );
-var floor = require( '@stdlib/math/base/special/floor' );
 var pkg = require( './../package.json' ).name;
 
 
@@ -54,9 +52,9 @@ bench( pkg+'::native', opts, function benchmark( b ) {
 	K = new Float64Array( len );
 	n = new Float64Array( len );
 	for ( i = 0; i < len; i++ ) {
-		N[ i ] = floor( uniform( 1.0, 100.0 ) );
-		K[ i ] = floor( randu() * N[ i ] );
-		n[ i ] = floor( randu() * N[ i ] );
+		N[ i ] = discreteUniform( 2, 100 );
+		n[ i ] = discreteUniform( 0, N[ i ] );
+		K[ i ] = discreteUniform( 0, N[ i ] );
 	}
 
 	b.tic();

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/benchmark/c/benchmark.c

@@ -16,11 +16,11 @@
 * limitations under the License.
 */
 
-#include "stdlib/math/base/special/round.h"
 #include "stdlib/stats/base/dists/hypergeometric/stdev.h"
-#include <math.h>
-#include <stdio.h>
+#include "stdlib/math/base/special/ceil.h"
 #include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <time.h>
 #include <sys/time.h>
 
@@ -94,17 +94,17 @@ static double random_uniform( const double min, const double max ) {
 */
 static double benchmark( void ) {
 	double elapsed;
-	double N[ 100 ];
-	double K[ 100 ];
-	double n[ 100 ];
+	int32_t N[ 100 ];
+	int32_t K[ 100 ];
+	int32_t n[ 100 ];
 	double sd;
 	double t;
 	int i;
 
 	for ( i = 0; i < 100; i++ ) {
-		N[ i ] = stdlib_base_round( random_uniform( 1.0, 100.0 ) );
-		K[ i ] = stdlib_base_round( random_uniform( 0.0, N[ i ] ) );
-		n[ i ] = stdlib_base_round( random_uniform( 0.0, N[ i ] ) );
+		N[ i ] = stdlib_base_ceil( random_uniform( 2.0, 100.0 ) );
+		K[ i ] = stdlib_base_ceil( random_uniform( 0.0, N[ i ] ) );
+		n[ i ] = stdlib_base_ceil( random_uniform( 0.0, N[ i ] ) );
 	}
 
 	t = tic();

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/examples/c/example.c

@@ -16,10 +16,11 @@
 * limitations under the License.
 */
 
-#include "stdlib/math/base/special/round.h"
 #include "stdlib/stats/base/dists/hypergeometric/stdev.h"
-#include <stdio.h>
+#include "stdlib/math/base/special/ceil.h"
 #include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
 
 static double random_uniform( const double min, const double max ) {
 	double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
@@ -28,16 +29,16 @@ static double random_uniform( const double min, const double max ) {
 
 int main( void ) {
 	double sd;
-	double N;
-	double K;
-	double n;
+	int32_t N;
+	int32_t K;
+	int32_t n;
 	int i;
 
 	for ( i = 0; i < 10; i++ ) {
-		N = stdlib_base_round( random_uniform( 0.0, 20.0 ) );
-		K = stdlib_base_round( random_uniform( 0.0, N ) );
-		n = stdlib_base_round( random_uniform( 0.0, K ) );
+		N = stdlib_base_ceil( random_uniform( 2.0, 100.0 ) );
+		K = stdlib_base_ceil( random_uniform( 0.0, N ) );
+		n = stdlib_base_ceil( random_uniform( 0.0, N ) );
 		sd = stdlib_base_dists_hypergeometric_stdev( N, K, n );
-		printf( "N: %lf, K: %lf, n: %lf, SD(X;N,K,n): %lf\n", N, K, n, sd );
+		printf( "N: %d, K: %d, n: %d, SD(X;N,K,n): %lf\n", N, K, n, sd );
 	}
 }

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/include/stdlib/stats/base/dists/hypergeometric/stdev.h

@@ -19,6 +19,8 @@
 #ifndef STDLIB_STATS_BASE_DISTS_HYPERGEOMETRIC_STDEV_H
 #define STDLIB_STATS_BASE_DISTS_HYPERGEOMETRIC_STDEV_H
 
+#include <stdint.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.
 */
@@ -27,14 +29,9 @@ extern "C" {
 #endif
 
 /**
-* Returns the standard deviation of a hypergeometric distribution with population size `N`, subpopulation size `K`, and number of draws `n`.
-*
-* @param N    population size
-* @param K    subpopulation size
-* @param n    number of draws
-* @return     standard deviation of the distribution
+* Returns the standard deviation of a hypergeometric distribution.
 */
-double stdlib_base_dists_hypergeometric_stdev( const double N, const double K, const double n );
+double stdlib_base_dists_hypergeometric_stdev( const int32_t N, const int32_t K, const int32_t n );
 
 #ifdef __cplusplus
 }

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/lib/native.js

@@ -26,13 +26,13 @@ var addon = require( './../src/addon.node' );
 // MAIN //
 
 /**
-* Returns the standard deviation of a hypergeometric distribution with population size `N`, subpopulation size `K`, and number of draws `n`.
+* Returns the standard deviation of a hypergeometric distribution.
 *
 * @private
-* @param {number} N - population size
-* @param {number} K - subpopulation size
-* @param {number} n - number of draws
-* @returns {number} standard deviation
+* @param {NonNegativeInteger} N - population size
+* @param {NonNegativeInteger} K - subpopulation size
+* @param {NonNegativeInteger} n - number of draws
+* @returns {NonNegativeNumber} standard deviation
 *
 * @example
 * var v = stdev( 16, 11, 4 );

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/manifest.json

@@ -39,7 +39,6 @@
       "libpath": [],
       "dependencies": [
         "@stdlib/math/base/napi/ternary",
-        "@stdlib/math/base/assert/is-nonnegative-integer",
         "@stdlib/constants/float64/pinf",
         "@stdlib/math/base/special/sqrt"
       ]
@@ -56,10 +55,9 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/math/base/assert/is-nonnegative-integer",
         "@stdlib/constants/float64/pinf",
         "@stdlib/math/base/special/sqrt",
-        "@stdlib/math/base/special/round"
+        "@stdlib/math/base/special/ceil"
       ]
     },
     {
@@ -74,10 +72,9 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/math/base/assert/is-nonnegative-integer",
-        "@stdlib/math/base/special/round",
         "@stdlib/constants/float64/pinf",
-        "@stdlib/math/base/special/sqrt"
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/math/base/special/ceil"
       ]
     }
   ]

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/src/addon.c

@@ -16,8 +16,8 @@
 * limitations under the License.
 */
 
-#include "stdlib/math/base/napi/ternary.h"
 #include "stdlib/stats/base/dists/hypergeometric/stdev.h"
+#include "stdlib/math/base/napi/ternary.h"
 
 // cppcheck-suppress shadowFunction
-STDLIB_MATH_BASE_NAPI_MODULE_DDD_D( stdlib_base_dists_hypergeometric_stdev )
+STDLIB_MATH_BASE_NAPI_MODULE_III_D( stdlib_base_dists_hypergeometric_stdev )

lib/node_modules/@stdlib/stats/base/dists/hypergeometric/stdev/src/main.c

@@ -16,10 +16,10 @@
 * limitations under the License.
 */
 
-#include "stdlib/constants/float64/pinf.h"
-#include "stdlib/math/base/assert/is_nonnegative_integer.h"
-#include "stdlib/math/base/special/sqrt.h"
 #include "stdlib/stats/base/dists/hypergeometric/stdev.h"
+#include "stdlib/math/base/special/sqrt.h"
+#include "stdlib/constants/float64/pinf.h"
+#include <stdint.h>
 
 /**
 * Returns the standard deviation of a hypergeometric distribution.
@@ -33,11 +33,11 @@
 * double sd = stdlib_base_dists_hypergeometric_stdev( 16, 11, 4 );
 * // returns ~0.829
 */
-double stdlib_base_dists_hypergeometric_stdev( const double N, const double K, const double n ) {
-	if ( !stdlib_base_is_nonnegative_integer( N ) || !stdlib_base_is_nonnegative_integer( K ) || !stdlib_base_is_nonnegative_integer( n ) || N == STDLIB_CONSTANT_FLOAT64_PINF || K == STDLIB_CONSTANT_FLOAT64_PINF || K > N || n > N ) {
-		return NAN;
+double stdlib_base_dists_hypergeometric_stdev( const int32_t N, const int32_t K, const int32_t n ) {
+	if (  N < 0 || K < 0 || n < 0 || N == STDLIB_CONSTANT_FLOAT64_PINF || K == STDLIB_CONSTANT_FLOAT64_PINF || K > N || n > N ) {
+		return 0.0/0.0; // NaN
 	}
-
-	double variance = n * ( K / N ) * ( ( N - K ) / N ) * ( ( N - n ) / ( N - 1 ) );
+	double p = (double)K / (double)N;
+	double variance = n * p * ( 1.0 - p ) * ( (double)(N-n) / (double)(N-1) );
 	return stdlib_base_sqrt( variance );
 }