refactor: reuse variance in stats/base/dists/betaprime/stdev

PR-URL: #11368
Reviewed-by: Athan Reines <kgryte@gmail.com>

Author: Om-A-osc

lib/node_modules/@stdlib/stats/base/dists/betaprime/stdev/lib/main.js

@@ -20,8 +20,8 @@
 
 // MODULES //
 
-var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
+var variance = require( '@stdlib/stats/base/dists/betaprime/variance' );
 
 
 // MAIN //
@@ -66,17 +66,7 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 * // returns NaN
 */
 function stdev( alpha, beta ) {
-	var bm1;
-	if (
-		isnan( alpha ) ||
-		alpha <= 0.0 ||
-		isnan( beta ) ||
-		beta <= 2.0
-	) {
-		return NaN;
-	}
-	bm1 = beta - 1.0;
-	return sqrt( ( alpha * ( alpha + bm1 ) ) / ( ( bm1-1.0 ) * bm1*bm1 ) );
+	return sqrt( variance( alpha, beta ) );
 }
 
 

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

@@ -39,8 +39,8 @@
       "libpath": [],
       "dependencies": [
         "@stdlib/math/base/napi/binary",
-        "@stdlib/math/base/assert/is-nan",
-        "@stdlib/math/base/special/sqrt"
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/stats/base/dists/betaprime/variance"
       ]
     },
     {
@@ -55,8 +55,8 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/math/base/assert/is-nan",
-        "@stdlib/math/base/special/sqrt"
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/stats/base/dists/betaprime/variance"
       ]
     },
     {
@@ -71,8 +71,8 @@
       "libraries": [],
       "libpath": [],
       "dependencies": [
-        "@stdlib/math/base/assert/is-nan",
-        "@stdlib/math/base/special/sqrt"
+        "@stdlib/math/base/special/sqrt",
+        "@stdlib/stats/base/dists/betaprime/variance"
       ]
     }
   ]

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

@@ -17,8 +17,8 @@
 */
 
 #include "stdlib/stats/base/dists/betaprime/stdev.h"
-#include "stdlib/math/base/assert/is_nan.h"
 #include "stdlib/math/base/special/sqrt.h"
+#include "stdlib/stats/base/dists/betaprime/variance.h"
 
 /**
 * Returns the standard deviation of a beta prime distribution.
@@ -32,15 +32,5 @@
 * // returns ~0.866
 */
 double stdlib_base_dists_betaprime_stdev( const double alpha, const double beta ) {
-	double bm1;
-	if (
-		stdlib_base_is_nan( alpha ) ||
-		stdlib_base_is_nan( beta ) ||
-		alpha <= 0.0 ||
-		beta <= 2.0
-	) {
-		return 0.0 / 0.0; // NaN
-	}
-	bm1 = beta - 1.0;
-	return stdlib_base_sqrt( ( alpha * ( alpha + bm1 ) ) / ( ( bm1 - 1.0 ) * bm1 * bm1 ) );
+	return stdlib_base_sqrt( stdlib_base_dists_betaprime_variance( alpha, beta ) );
 }