refactor: remove hardcoded constant

PR-URL: #2970
Reviewed-by: Athan Reines <[email protected]>

Author: gunjjoshi

lib/node_modules/@stdlib/math/base/special/falling-factorial/lib/main.js

@@ -41,11 +41,7 @@ var floor = require( '@stdlib/math/base/special/floor' );
 var abs = require( '@stdlib/math/base/special/abs' );
 var FLOAT64_MAX = require( '@stdlib/constants/float64/max' );
 var PINF = require( '@stdlib/constants/float64/pinf' );
-
-
-// VARIABLES //
-
-var MAX_FACTORIAL = 170; // TODO: consider packaging as constant
+var FLOAT64_MAX_SAFE_NTH_FACTORIAL = require( '@stdlib/constants/float64/max-safe-nth-factorial' ); // eslint-disable-line id-length
 
 
 // FUNCTIONS //
@@ -181,10 +177,10 @@ function fallingFactorial( x, n ) {
 	}
 	if ( x < 0.5 ) {
 		// Computing `1 + x` will throw away digits, so split up calculation...
-		if ( n > MAX_FACTORIAL-2 ) {
+		if ( n > FLOAT64_MAX_SAFE_NTH_FACTORIAL-2 ) {
 			// Given a ratio of two very large numbers, we need to split the calculation up into two blocks:
-			t1 = x * fallingFactorial( x-1.0, MAX_FACTORIAL-2 );
-			t2 = fallingFactorial( x-MAX_FACTORIAL+1.0, n-MAX_FACTORIAL+1 );
+			t1 = x * fallingFactorial( x-1.0, FLOAT64_MAX_SAFE_NTH_FACTORIAL-2 ); // eslint-disable-line max-len
+			t2 = fallingFactorial( x-FLOAT64_MAX_SAFE_NTH_FACTORIAL+1.0, n-FLOAT64_MAX_SAFE_NTH_FACTORIAL+1 ); // eslint-disable-line max-len
 			if ( FLOAT64_MAX/abs(t1) < abs(t2) ) {
 				return PINF;
 			}