bench: move random number generation outside the benchmarking loops

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---

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

@@ -21,8 +21,9 @@
 // MODULES //
 
 var bench = require( '@stdlib/bench' );
-var ceil = require( '@stdlib/math/base/special/ceil' );
-var randu = require( '@stdlib/random/base/randu' );
+var Float64Array = require( '@stdlib/array/float64' );
+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 pkg = require( './../package.json' ).name;
 var cdf = require( './../lib' );
@@ -31,16 +32,23 @@ var cdf = require( './../lib' );
 // MAIN //
 
 bench( pkg, function benchmark( b ) {
+	var len;
 	var k;
 	var x;
 	var y;
 	var i;
 
+	len = 100;
+	x = new Float64Array( len );
+	k = new Float64Array( len );
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = uniform( 0.0, 100.0 );
+		k[ i ] = discreteUniform( 1, 100 );
+	}
+
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {
-		x = randu() * 100.0;
-		k = ceil( randu()*100.0 );
-		y = cdf( x, k );
+		y = cdf( x[ i % len ], k[ i % len ] );
 		if ( isnan( y ) ) {
 			b.fail( 'should not return NaN' );
 		}
@@ -55,18 +63,23 @@ bench( pkg, function benchmark( b ) {
 
 bench( pkg+':factory', function benchmark( b ) {
 	var mycdf;
+	var len;
 	var k;
 	var x;
 	var y;
 	var i;
 
 	k = 10.0;
 	mycdf = cdf.factory( k );
+	len = 100;
+	x = new Float64Array( len );
+	for ( i = 0; i < len; i++ ) {
+		x[ i ] = uniform( 0.0, 100.0 );
+	}
 
 	b.tic();
 	for ( i = 0; i < b.iterations; i++ ) {
-		x = randu() * 100.0;
-		y = mycdf( x );
+		y = mycdf( x[ i % len ] );
 		if ( isnan( y ) ) {
 			b.fail( 'should not return NaN' );
 		}