refactor: use is-nonnegative-integer

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---

Author: gunjjoshi

lib/node_modules/@stdlib/math/base/special/factorial2/lib/main.js

@@ -21,7 +21,7 @@
 // MODULES //
 
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
-var isInteger = require( '@stdlib/math/base/assert/is-integer' );
+var isNonnegativeInteger = require( '@stdlib/math/base/assert/is-nonnegative-integer' );
 var isEven = require( '@stdlib/math/base/assert/is-even' );
 var PINF = require( '@stdlib/constants/float64/pinf' );
 var FLOAT64_MAX_NTH_DOUBLE_FACTORIAL = require( '@stdlib/constants/float64/max-nth-double-factorial' ); // eslint-disable-line id-length
@@ -56,15 +56,12 @@ function factorial2( n ) {
 	var out;
 	var v;
 	var i;
-	if ( isnan( n ) ) {
+	if ( isnan( n ) || !isNonnegativeInteger( n ) ) {
 		return NaN;
 	}
 	if ( n > FLOAT64_MAX_NTH_DOUBLE_FACTORIAL ) {
 		return PINF;
 	}
-	if ( n < 0 || isInteger( n ) === false ) {
-		return NaN;
-	}
 	v = n|0; // asm type annotation
 	if ( v === 0|0 || v === 1|0 ) {
 		return 1|0; // asm type annotation

lib/node_modules/@stdlib/math/base/special/factorial2/manifest.json

@@ -40,7 +40,7 @@
         "@stdlib/math/base/assert/is-even",
         "@stdlib/constants/float64/pinf",
         "@stdlib/constants/float64/max-nth-double-factorial",
-        "@stdlib/math/base/assert/is-integer"
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     },
     {
@@ -57,7 +57,7 @@
         "@stdlib/math/base/assert/is-even",
         "@stdlib/constants/float64/pinf",
         "@stdlib/constants/float64/max-nth-double-factorial",
-        "@stdlib/math/base/assert/is-integer"
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     },
     {
@@ -74,7 +74,7 @@
         "@stdlib/math/base/assert/is-even",
         "@stdlib/constants/float64/pinf",
         "@stdlib/constants/float64/max-nth-double-factorial",
-        "@stdlib/math/base/assert/is-integer"
+        "@stdlib/math/base/assert/is-nonnegative-integer"
       ]
     }
   ]

lib/node_modules/@stdlib/math/base/special/factorial2/src/main.c

@@ -18,7 +18,7 @@
 
 #include "stdlib/math/base/special/factorial2.h"
 #include "stdlib/math/base/assert/is_even.h"
-#include "stdlib/math/base/assert/is_integer.h"
+#include "stdlib/math/base/assert/is_nonnegative_integer.h"
 #include "stdlib/constants/float64/pinf.h"
 #include "stdlib/constants/float64/max_nth_double_factorial.h"
 
@@ -37,7 +37,7 @@ double stdlib_base_factorial2( const double n ) {
 	double out;
 	double v;
 	double i;
-	if ( !stdlib_base_is_integer( n ) || n < 0.0 ) {
+	if ( !stdlib_base_is_nonnegative_integer( n ) ) {
 		return 0.0 / 0.0; // NaN
 	}
 	if ( n > STDLIB_CONSTANT_FLOAT64_MAX_NTH_DOUBLE_FACTORIAL ) {