bench: refactor random number generation in stats/base/dists/laplace

PR-URL: #5270
Closes: #4976

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>
Reviewed-by: Karan Anand <anandkaranubc@users.noreply.github.com>

Author: gkbishnoi07

lib/node_modules/@stdlib/stats/base/dists/laplace/cdf/benchmark/benchmark.js

@@ -21,7 +21,8 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var randu = require( '@stdlib/random/base/randu' );
+var Float64Array = require( '@stdlib/array/float64' );
+var uniform = require( '@stdlib/random/base/uniform' );
 var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var EPS = require( '@stdlib/constants/float64/eps' );
 var pkg = require( './../package.json' ).name;
@@ -32,17 +33,25 @@ var cdf = require( './../lib' );
 
 bench( pkg, function benchmark( b ) {
 	var scale;
+	var len;
 	var mu;
 	var x;
 	var y;
 	var i;
 
+	len = 100;
+	mu = new Float64Array( len );
+	scale = new Float64Array( len );
+	x = new Float64Array( len );
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = uniform( -100.0, 100.0 );
+		mu[ i ] = uniform( -50.0, 50.0 );
+		scale[ i ] = uniform( EPS, 20.0 );
+	}
+
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {
-		x = ( randu()*200.0 ) - 100;
-		mu = ( randu()*100.0 ) - 50.0;
-		scale = ( randu()*20.0 ) + EPS;
-		y = cdf( x, mu, scale );
+		y = cdf( x[ i % len ], mu[ i % len ], scale[ i % len ] );
 		if ( isnan( y ) ) {
 			b.fail( 'should not return NaN' );
 		}
@@ -58,19 +67,24 @@ bench( pkg, function benchmark( b ) {
 bench( pkg+':factory', function benchmark( b ) {
 	var mycdf;
 	var scale;
+	var len;
 	var mu;
 	var x;
 	var y;
 	var i;
 
 	mu = 0.0;
 	scale = 1.5;
+	len = 100;
+	x = new Float64Array( len );
 	mycdf = cdf.factory( mu, scale );
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = uniform( -2.0, 2.0 );
+	}
 
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {
-		x = ( randu()*4.0 ) - 2.0;
-		y = mycdf( x );
+		y = mycdf( x[ i % len ] );
 		if ( isnan( y ) ) {
 			b.fail( 'should not return NaN' );
 		}