diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/README.md b/lib/node_modules/@stdlib/stats/incr/nanprod/README.md
new file mode 100644
index 000000000000..027d5d882b75
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/README.md
@@ -0,0 +1,198 @@
+
+
+# incrnanprod
+
+> Compute a product incrementally, ignoring `NaN` values.
+
+
+
+The product is defined as
+
+
+
+```math
+p = \prod_{i=0}^{n-1} x_i
+```
+
+
+
+
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var incrnanprod = require( '@stdlib/stats/incr/nanprod' );
+```
+
+#### incrnanprod()
+
+Returns an accumulator `function` which incrementally computes a product, ignoring `NaN` values.
+
+```javascript
+var accumulator = incrnanprod();
+```
+
+#### accumulator( \[x] )
+
+If provided an input value `x`, the accumulator function returns an updated product. If not provided an input value `x`, the accumulator function returns the current product.
+
+```javascript
+var accumulator = incrnanprod();
+
+var prod = accumulator( 2.0 );
+// returns 2.0
+
+prod = accumulator( NaN );
+// returns 2.0
+
+prod = accumulator( 1.0 );
+// returns 2.0
+
+prod = accumulator( 3.0 );
+// returns 6.0
+
+prod = accumulator();
+// returns 6.0
+```
+
+Under certain conditions, overflow may be transient.
+
+```javascript
+// Large values:
+var x = 5.0e+300;
+var y = 1.0e+300;
+
+// Tiny value:
+var z = 2.0e-302;
+
+// Initialize an accumulator:
+var accumulator = incrnanprod();
+
+var prod = accumulator( x );
+// returns 5.0e+300
+
+// Transient overflow:
+prod = accumulator( y );
+// returns Infinity
+
+// Recover a finite result:
+prod = accumulator( z );
+// returns 1.0e+299
+```
+
+Similarly, under certain conditions, underflow may be transient.
+
+```javascript
+// Tiny values:
+var x = 4.0e-302;
+var y = 9.0e-303;
+
+// Large value:
+var z = 2.0e+300;
+
+// Initialize an accumulator:
+var accumulator = incrnanprod();
+
+var prod = accumulator( x );
+// returns 4.0e-302
+
+// Transient underflow:
+prod = accumulator( y );
+// returns 0.0
+
+// Recover a non-zero result:
+prod = accumulator( z );
+// returns 7.2e-304
+```
+
+
+
+
+
+
+
+## Notes
+
+- Input values are **not** type checked. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
+- For long running accumulations or accumulations of either large or small numbers, care should be taken to prevent overflow and underflow. Note, however, that overflow/underflow may be transient, as the accumulator does not use a double-precision floating-point number to store an accumulated product. Instead, the accumulator splits an accumulated product into a normalized **fraction** and **exponent** and updates each component separately. Doing so guards against a loss in precision.
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var uniform = require( '@stdlib/random/base/uniform' );
+var bernoulli = require( '@stdlib/random/base/bernoulli' );
+var incrnanprod = require( '@stdlib/stats/incr/nanprod' );
+
+var accumulator;
+var v;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnanprod();
+
+// For each simulated value, update the product...
+for ( i = 0; i < 100; i++ ) {
+ v = ( bernoulli( 0.8 ) < 1 ) ? NaN : uniform( 0.0, 100.0 );
+ accumulator( v );
+}
+console.log( accumulator() );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/incr/nanprod/benchmark/benchmark.js
new file mode 100644
index 000000000000..9e9c5a74613e
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/benchmark/benchmark.js
@@ -0,0 +1,69 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var randu = require( '@stdlib/random/base/randu' );
+var pkg = require( './../package.json' ).name;
+var incrnanprod = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var f;
+ var i;
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ f = incrnanprod();
+ if ( typeof f !== 'function' ) {
+ b.fail( 'should return a function' );
+ }
+ }
+ b.toc();
+ if ( typeof f !== 'function' ) {
+ b.fail( 'should return a function' );
+ }
+ b.pass( 'benchmark finished' );
+ b.end();
+});
+
+bench( pkg+'::accumulator', function benchmark( b ) {
+ var acc;
+ var v;
+ var i;
+
+ acc = incrnanprod();
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ v = acc( randu()*10.0 );
+ if ( v !== v ) {
+ b.fail( 'should not return NaN' );
+ }
+ }
+ b.toc();
+ if ( v !== v ) {
+ b.fail( 'should not return NaN' );
+ }
+ b.pass( 'benchmark finished' );
+ b.end();
+});
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/docs/repl.txt b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/repl.txt
new file mode 100644
index 000000000000..4094ae4e0b7b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/repl.txt
@@ -0,0 +1,38 @@
+
+{{alias}}()
+ Returns an accumulator function which incrementally computes a
+ product, ignoring `NaN` values.
+
+ If provided a value, the accumulator function returns an updated product. If
+ not provided a value, the accumulator function returns the current product.
+
+ For long running accumulations or accumulations of large numbers, care
+ should be taken to prevent overflow. Note, however, that overflow/underflow
+ may be transient, as the accumulator does not use a double-precision
+ floating-point number to store an accumulated product. Instead, the
+ accumulator splits an accumulated product into a normalized fraction and
+ exponent and updates each component separately. Doing so guards against a
+ loss in precision.
+
+ Returns
+ -------
+ acc: Function
+ Accumulator function.
+
+ Examples
+ --------
+ > var accumulator = {{alias}}();
+ > var v = accumulator()
+ null
+ > v = accumulator( 2.0 )
+ 2.0
+ > v = accumulator( NaN )
+ 2.0
+ > v = accumulator( -5.0 )
+ -10.0
+ > v = accumulator()
+ -10.0
+
+ See Also
+ --------
+
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/index.d.ts
new file mode 100644
index 000000000000..a708b9f7dda3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/index.d.ts
@@ -0,0 +1,66 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+// TypeScript Version: 4.1
+
+///
+
+/**
+* If provided a value, returns an updated product; otherwise, returns the current product.
+*
+* ## Notes
+*
+* - For long running accumulations or accumulations of large numbers, care should be taken to prevent overflow. Note, however, that overflow/underflow may be transient, as the accumulator does not use a double-precision floating-point number to store an accumulated product. Instead, the accumulator splits an accumulated product into a normalized fraction and exponent and updates each component separately. Doing so guards against a loss in precision.
+*
+* @param x - value
+* @returns product
+*/
+type accumulator = ( x?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes a product, ignoring `NaN` values.
+*
+* @returns accumulator function
+*
+* @example
+* var accumulator = incrnanprod();
+*
+* var v = accumulator();
+* // returns null
+*
+* v = accumulator( 2.0 );
+* // returns 2.0
+*
+* v = accumulator( NaN );
+* // returns 2.0
+*
+* v = accumulator( 3.0 );
+* // returns 6.0
+*
+* v = accumulator( 4.0 );
+* // returns 24.0
+*
+* v = accumulator();
+* // returns 24.0
+*/
+declare function incrnanprod(): accumulator;
+
+
+// EXPORTS //
+
+export = incrnanprod;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/test.ts b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/test.ts
new file mode 100644
index 000000000000..ea52ed039bf5
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/docs/types/test.ts
@@ -0,0 +1,61 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+import incrnanprod = require( './index' );
+
+
+// TESTS //
+
+// The function returns an accumulator function...
+{
+ incrnanprod(); // $ExpectType accumulator
+}
+
+// The compiler throws an error if the function is provided arguments...
+{
+ incrnanprod( '5' ); // $ExpectError
+ incrnanprod( 5 ); // $ExpectError
+ incrnanprod( true ); // $ExpectError
+ incrnanprod( false ); // $ExpectError
+ incrnanprod( null ); // $ExpectError
+ incrnanprod( undefined ); // $ExpectError
+ incrnanprod( [] ); // $ExpectError
+ incrnanprod( {} ); // $ExpectError
+ incrnanprod( ( x: number ): number => x ); // $ExpectError
+}
+
+// The function returns an accumulator function which returns an accumulated result...
+{
+ const acc = incrnanprod();
+
+ acc(); // $ExpectType number | null
+ acc( 3.14 ); // $ExpectType number | null
+}
+
+// The compiler throws an error if the returned accumulator function is provided invalid arguments...
+{
+ const acc = incrnanprod();
+
+ acc( '5' ); // $ExpectError
+ acc( true ); // $ExpectError
+ acc( false ); // $ExpectError
+ acc( null ); // $ExpectError
+ acc( [] ); // $ExpectError
+ acc( {} ); // $ExpectError
+ acc( ( x: number ): number => x ); // $ExpectError
+}
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/examples/index.js b/lib/node_modules/@stdlib/stats/incr/nanprod/examples/index.js
new file mode 100644
index 000000000000..fbc95c874d0b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/examples/index.js
@@ -0,0 +1,40 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+var uniform = require( '@stdlib/random/base/uniform' );
+var bernoulli = require( '@stdlib/random/base/bernoulli' );
+var incrnanprod = require( './../lib' );
+
+var accumulator;
+var prod;
+var v;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnanprod();
+
+// For each simulated value, update the product...
+console.log( '\nValue\tProduct\n' );
+for ( i = 0; i < 100; i++ ) {
+ v = ( bernoulli( 0.8 ) < 1 ) ? NaN : uniform( 0.0, 100.0 );
+ prod = accumulator( v );
+ console.log( '%s\t%s', ( v === v ) ? v.toFixed( 4 ) : 'NaN', ( prod === null ) ? 'null' : prod.toFixed( 4 ) );
+}
+console.log( '\nFinal product: %d\n', accumulator() );
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/lib/index.js b/lib/node_modules/@stdlib/stats/incr/nanprod/lib/index.js
new file mode 100644
index 000000000000..c405aeba148b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/lib/index.js
@@ -0,0 +1,54 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+/**
+* Compute a product incrementally, while ignoring `NaN` values.
+*
+* @module @stdlib/stats/incr/nanprod
+*
+* @example
+* var incrnanprod = require( '@stdlib/stats/incr/nanprod' );
+*
+* var accumulator = incrnanprod();
+*
+* var prod = accumulator();
+* // returns null
+*
+* prod = accumulator( 2.0 );
+* // returns 2.0
+*
+* prod = accumulator( NaN );
+* // returns 2.0
+*
+* prod = accumulator( -5.0 );
+* // returns -10.0
+*
+* prod = accumulator();
+* // returns -10.0
+*/
+
+// MODULES //
+
+var main = require( './main.js' );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/lib/main.js b/lib/node_modules/@stdlib/stats/incr/nanprod/lib/main.js
new file mode 100644
index 000000000000..7cf427dad326
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/lib/main.js
@@ -0,0 +1,74 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var incrprod = require( '@stdlib/stats/incr/prod' );
+
+
+// MAIN //
+
+/**
+* Returns an accumulator function which incrementally computes a product, ignoring `NaN` values.
+*
+* @returns {Function} accumulator function
+*
+* @example
+* var accumulator = incrnanprod();
+*
+* var prod = accumulator();
+* // returns null
+*
+* prod = accumulator( 2.0 );
+* // returns 2.0
+*
+* prod = accumulator( NaN );
+* // returns 2.0
+*
+* prod = accumulator( -5.0 );
+* // returns -10.0
+*
+* prod = accumulator();
+* // returns -10.0
+*/
+function incrnanprod() {
+ var prod = incrprod();
+ return accumulator;
+
+ /**
+ * If provided a value, the accumulator function returns an updated product. If not provided a value, the accumulator function returns the current product.
+ *
+ * @private
+ * @param {number} [x] - new value
+ * @returns {(number|null)} product or null
+ */
+ function accumulator( x ) {
+ if ( arguments.length === 0 || isnan( x ) ) {
+ return prod();
+ }
+ return prod( x );
+ }
+}
+
+
+// EXPORTS //
+
+module.exports = incrnanprod;
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/package.json b/lib/node_modules/@stdlib/stats/incr/nanprod/package.json
new file mode 100644
index 000000000000..6cb9ddb39f86
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/package.json
@@ -0,0 +1,65 @@
+{
+ "name": "@stdlib/stats/incr/nanprod",
+ "version": "0.0.0",
+ "description": "Compute a product incrementally, ignoring NaN values.",
+ "license": "Apache-2.0",
+ "author": {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ },
+ "contributors": [
+ {
+ "name": "The Stdlib Authors",
+ "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+ }
+ ],
+ "main": "./lib",
+ "directories": {
+ "benchmark": "./benchmark",
+ "doc": "./docs",
+ "example": "./examples",
+ "lib": "./lib",
+ "test": "./test"
+ },
+ "types": "./docs/types",
+ "scripts": {},
+ "homepage": "https://github.com/stdlib-js/stdlib.git",
+ "repository": {
+ "type": "git",
+ "url": "git://github.com/stdlib-js/stdlib.git"
+ },
+ "bugs": {
+ "url": "https://github.com/stdlib-js/stdlib/issues"
+ },
+ "dependencies": {},
+ "devDependencies": {},
+ "engines": {
+ "node": ">=0.10.0",
+ "npm": ">2.7.0"
+ },
+ "os": [
+ "aix",
+ "darwin",
+ "freebsd",
+ "linux",
+ "macos",
+ "openbsd",
+ "sunos",
+ "win32",
+ "windows"
+ ],
+ "keywords": [
+ "stdlib",
+ "stdmath",
+ "statistics",
+ "stats",
+ "mathematics",
+ "math",
+ "multiplication",
+ "mult",
+ "product",
+ "prod",
+ "incremental",
+ "accumulator"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/incr/nanprod/test/test.js b/lib/node_modules/@stdlib/stats/incr/nanprod/test/test.js
new file mode 100644
index 000000000000..a275b34031cf
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nanprod/test/test.js
@@ -0,0 +1,326 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var PINF = require( '@stdlib/constants/float64/pinf' );
+var NINF = require( '@stdlib/constants/float64/ninf' );
+var EPSILON = require( '@stdlib/constants/float64/eps' );
+var normal = require( '@stdlib/random/base/normal' );
+var ldexp = require( '@stdlib/math/base/special/ldexp' );
+var abs = require( '@stdlib/math/base/special/abs' );
+var isnan = require( '@stdlib/assert/is-nan' );
+var isEven = require( '@stdlib/math/base/assert/is-even' );
+var isNegativeZero = require( '@stdlib/math/base/assert/is-negative-zero' );
+var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
+var incrnanprod = require( './../lib' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof incrnanprod, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'the function returns an accumulator function', function test( t ) {
+ t.strictEqual( typeof incrnanprod(), 'function', 'returns a function' );
+ t.end();
+});
+
+tape( 'the initial accumulator value is `null`', function test( t ) {
+ var acc = incrnanprod();
+ t.strictEqual( acc(), null, 'returns null' );
+ t.end();
+});
+
+tape( 'the accumulator function incrementally computes a product', function test( t ) {
+ var expected;
+ var actual;
+ var data;
+ var prod;
+ var acc;
+ var N;
+ var d;
+ var i;
+
+ data = [ 2.0, NaN, 3.0, 2.0, NaN, 4.0, 3.0, 4.0 ];
+ N = data.length;
+
+ expected = [];
+ actual = [];
+
+ acc = incrnanprod();
+
+ prod = 1.0;
+ for ( i = 0; i < N; i++ ) {
+ d = data[ i ];
+ if ( !isnan( d ) ) {
+ prod *= d;
+ }
+ expected[ i ] = prod;
+ actual[ i ] = acc( d );
+ }
+ t.deepEqual( actual, expected, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if not provided an input value, the accumulator function returns the current product', function test( t ) {
+ var data;
+ var acc;
+ var i;
+
+ data = [ 2.0, NaN, 3.0, 1.0 ];
+
+ acc = incrnanprod();
+ for ( i = 0; i < data.length; i++ ) {
+ acc( data[ i ] );
+ }
+ t.strictEqual( acc(), 6.0, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the accumulator function incrementally computes a product (special series)', function test( t ) {
+ var acc;
+ var x;
+ var i;
+
+ acc = incrnanprod();
+ x = 2;
+
+ // A series of reciprocals having an even number of terms is equal to unity...
+ for ( i = 0; i < 150; i++ ) {
+ if ( isEven( i ) ) {
+ acc( x );
+ } else {
+ acc( 1.0/x );
+ }
+ if ( i % 10 === 0 ) {
+ acc( NaN );
+ }
+ }
+ t.strictEqual( acc(), 1.0, 'returns expected value' );
+ t.end();
+});
+
+tape( 'the accumulator function can return a result which overflows', function test( t ) {
+ var acc = incrnanprod();
+
+ acc( 5.0e300 );
+ acc( NaN );
+ acc( 1.0e300 );
+
+ t.strictEqual( acc(), PINF, 'returns infinity' );
+ t.end();
+});
+
+tape( 'overflow may be transient', function test( t ) {
+ var expected;
+ var delta;
+ var tol;
+ var acc;
+ var x;
+ var y;
+ var z;
+
+ expected = ldexp( 0.01, 1000 );
+
+ acc = incrnanprod();
+
+ x = ldexp( 0.5, 1000 ); // ~5.4e300
+ y = ldexp( 0.1, 1000 ); // ~1.1e300
+ z = ldexp( 0.2, -1000 ); // ~1.87e-302
+
+ acc( x );
+ acc( NaN );
+ acc( y );
+ acc( z );
+
+ delta = abs( expected - acc() );
+ tol = EPSILON * abs( expected );
+
+ t.strictEqual( delta <= tol, true, 'within tolerance. Expected: '+expected+'. Actual: '+acc()+'. Delta: '+delta+'. Tol: '+tol+'.' );
+ t.end();
+});
+
+tape( 'the accumulator function can return a result which underflows', function test( t ) {
+ var acc = incrnanprod();
+
+ acc( 4.0e-302 );
+ acc( NaN );
+ acc( 9.0e-303 );
+
+ t.strictEqual( acc(), 0.0, 'returns 0' );
+ t.end();
+});
+
+tape( 'underflow may be transient', function test( t ) {
+ var expected;
+ var delta;
+ var tol;
+ var acc;
+ var x;
+ var y;
+ var z;
+
+ expected = ldexp( 0.01, -1000 );
+
+ acc = incrnanprod();
+
+ x = ldexp( 0.5, -1000 ); // ~4.67e-302
+ y = ldexp( 0.1, -1000 ); // ~9.33e-303
+ z = ldexp( 0.2, 1000 ); // ~2.14e300
+
+ acc( x );
+ acc( NaN );
+ acc( y );
+
+ t.strictEqual( acc(), 0.0, 'returns 0 due to underflow' );
+
+ acc( z );
+
+ delta = abs( acc() - expected );
+ tol = EPSILON * abs( expected );
+
+ t.strictEqual( delta <= tol, true, 'within tolerance. Expected: '+expected+'. Actual: '+acc()+'. Delta: '+delta+'. Tol: '+tol+'.' );
+ t.end();
+});
+
+tape( 'if provided `+infinity`, the accumulator function always returns `NaN` if also provided a `0`', function test( t ) {
+ var acc;
+ var p;
+ var i;
+
+ acc = incrnanprod();
+ acc( 5.0 );
+
+ t.strictEqual( acc(), 5.0, 'returns expected value' );
+
+ acc( PINF );
+ t.strictEqual( acc(), PINF, 'returns +infinity' );
+
+ acc( NaN );
+ t.strictEqual( acc(), PINF, 'ignores NaN and retains +infinity' );
+
+ acc( 0.0 );
+ t.strictEqual( isnan( acc() ), true, 'returns NaN' );
+
+ for ( i = 0; i < 1000; i++ ) {
+ p = acc( i + 1 );
+ t.strictEqual( isnan( p ), true, 'returns NaN' );
+ }
+ t.end();
+});
+
+tape( 'if provided `-infinity`, the accumulator function always returns `NaN` if also provided a `0`', function test( t ) {
+ var acc;
+ var p;
+ var i;
+
+ acc = incrnanprod();
+ acc( 5.0 );
+
+ t.strictEqual( acc(), 5.0, 'returns expected value' );
+
+ acc( NINF );
+ t.strictEqual( acc(), NINF, 'returns -infinity' );
+
+ acc( NaN );
+ t.strictEqual( acc(), NINF, 'ignores NaN and retains -infinity' );
+
+ acc( 0.0 );
+ t.strictEqual( isnan( acc() ), true, 'returns NaN' );
+
+ for ( i = 0; i < 1000; i++ ) {
+ p = acc( i+1 );
+ t.strictEqual( isnan( p ), true, 'returns NaN' );
+ }
+ t.end();
+});
+
+tape( 'if provided `0`, the accumulator function always returns `0` (no +-infinity)', function test( t ) {
+ var acc;
+ var p;
+ var i;
+
+ acc = incrnanprod();
+ acc( 5.0 );
+
+ t.strictEqual( acc(), 5.0, 'returns expected value' );
+
+ acc( NaN );
+ t.strictEqual( acc(), 5.0, 'ignores NaN and retains product' );
+
+ acc( 0.0 );
+ t.strictEqual( acc(), 0.0, 'returns 0.0' );
+
+ for ( i = 0; i < 1000; i++ ) {
+ p = acc( i+1 );
+ t.strictEqual( p, 0.0, 'returns 0.0' );
+ }
+ t.end();
+});
+
+tape( 'the accumulator function returns a signed zero', function test( t ) {
+ var acc;
+ var p;
+ var i;
+
+ acc = incrnanprod();
+ acc( -0.0 );
+ for ( i = 0; i < 100; i++ ) {
+ acc( NaN );
+ p = acc( -0.0 );
+ if ( isEven( i ) ) {
+ t.strictEqual( isPositiveZero( p ), true, 'returns +0' );
+ } else {
+ t.strictEqual( isNegativeZero( p ), true, 'returns -0' );
+ }
+ }
+ t.end();
+});
+
+tape( 'if provided values of normal magnitude (i.e., far away from the extremes), the accumulator function returns results matching naive multiplication', function test( t ) {
+ var randn;
+ var prod;
+ var acc;
+ var r;
+ var i;
+
+ acc = incrnanprod();
+
+ randn = normal.factory( 50.0, 10.0, {
+ 'seed': 1234
+ });
+
+ prod = 1.0;
+ for ( i = 0; i < 1000; i++ ) {
+ r = randn();
+ if ( isnan( r ) ) {
+ continue;
+ }
+ acc( r );
+ prod *= r;
+ }
+ t.strictEqual( acc(), prod, 'equals native multiplication' );
+ t.end();
+});