feat: add stats/incr/nansumprod

lib/node_modules/@stdlib/stats/incr/nansumprod/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2025 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.
+
+-->
+
+# incrnansumprod
+
+> Compute a sum of products incrementally ignoring `NaN` values.
+
+<section class="intro">
+
+The sum of products is defined as
+
+<!-- <equation class="equation" label="eq:sum_product" align="center" raw="s = \sum_{i=0}^{n-1} x_i y_i" alt="Equation for the sum of products."> -->
+
+```math
+s = \sum_{i=0}^{n-1} x_i y_i
+```
+
+<!-- <div class="equation" align="center" data-raw-text="s = \sum_{i=0}^{n-1} x_i y_i" data-equation="eq:sum_product">
+    <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@49d8cabda84033d55d7b8069f19ee3dd8b8d1496/lib/node_modules/@stdlib/stats/incr/nansumprod/docs/img/equation_sum_product.svg" alt="Equation for the sum of products.">
+    <br>
+</div> -->
+
+<!-- </equation> -->
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var incrnansumprod = require( '@stdlib/stats/incr/nansumprod' );
+```
+
+#### incrnansumprod()
+
+Returns an accumulator `function` which incrementally computes a sum of products, ignoring `NaN` values.
+
+```javascript
+var accumulator = incrnansumprod();
+```
+
+#### accumulator( \[x, y] )
+
+If provided input values `x` and `y`, the accumulator function returns an updated sum. If not provided input value `x` and `y`, the accumulator function returns the current sum.
+
+```javascript
+var accumulator = incrnansumprod();
+
+var sum = accumulator( 2.0, 3.0 );
+// returns 6.0
+
+sum = accumulator( 1.0, -1.0 );
+// returns 5.0
+
+sum = accumulator( NaN, NaN );
+// returns 5.0
+
+sum = accumulator( 3, NaN );
+// returns 5.0
+
+sum = accumulator( 3.0, 4.0 );
+// returns 17.0
+
+sum = accumulator();
+// returns 17.0
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## 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 large numbers, care should be taken to prevent overflow.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var incrnansumprod = require( '@stdlib/stats/incr/nansumprod' );
+
+var accumulator;
+var v1;
+var v2;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnansumprod();
+
+// For each simulated datum, update the sum-product...
+for ( i = 0; i < 100; i++ ) {
+    if ( randu() < 0.2 ) {
+        v1 = NaN;
+        v2 = NaN;
+    } else if ( randu() < 0.3 ) {
+        v1 = NaN;
+        v2 = randu() * 100.0;
+    } else {
+        v1 = randu() * 100.0;
+        v2 = randu() * 100.0;
+    }
+    accumulator( v1, v2 );
+}
+console.log( accumulator() );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+* * *
+
+## See Also
+
+-   <span class="package-name">[`@stdlib/stats/incr/sumprod`][@stdlib/stats/incr/sumprod]</span><span class="delimiter">: </span><span class="description">Compute a sum of products incrementally.</span>
+-   <span class="package-name">[`@stdlib/stats/incr/nansum`][@stdlib/stats/incr/nansum]</span><span class="delimiter">: </span><span class="description">Compute a sum incrementally, ignoring `NaN` values.</span>
+-   <span class="package-name">[`@stdlib/stats/incr/prod`][@stdlib/stats/incr/prod]</span><span class="delimiter">: </span><span class="description">compute a product incrementally.</span>
+-   <span class="package-name">[`@stdlib/stats/incr/sum`][@stdlib/stats/incr/sum]</span><span class="delimiter">: </span><span class="description">compute a sum incrementally.</span>
+
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+<!-- <related-links> -->
+
+[@stdlib/stats/incr/sumprod]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/sumprod
+
+[@stdlib/stats/incr/prod]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/prod
+
+[@stdlib/stats/incr/sum]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/sum
+
+[@stdlib/stats/incr/nansum]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/nansum
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/stats/incr/nansumprod/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 incrnansumprod = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var f;
+	var i;
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		f = incrnansumprod();
+		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 = incrnansumprod();
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = acc( randu()*10.0, 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();
+});

lib/node_modules/@stdlib/stats/incr/nansumprod/docs/repl.txt

@@ -0,0 +1,34 @@
+
+{{alias}}()
+    Returns an accumulator function which incrementally computes a sum of
+    products, ignoring `NaN` values.
+
+    If provided input values, the accumulator function returns an updated sum.
+    If not provided input values, the accumulator function returns the current
+    sum.
+
+    For long running accumulations or accumulations of large numbers, care
+    should be taken to prevent overflow.
+
+    Returns
+    -------
+    acc: Function
+        Accumulator function.
+
+    Examples
+    --------
+    > var accumulator = {{alias}}();
+    > var s = accumulator()
+    null
+    > s = accumulator( 2.0, 3.0 )
+    6.0
+    > s = accumulator( -5.0, 2.0 )
+    -4.0
+    > s = accumulator( NaN, 6.0 )
+    -4.0
+    > s = accumulator()
+    -4.0
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/stats/incr/nansumprod/docs/types/index.d.ts

@@ -0,0 +1,60 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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
+
+/// <reference types="@stdlib/types"/>
+
+/**
+* If provided arguments, returns an updated sum of products; otherwise, returns the current sum of products.
+*
+* @param x - value
+* @param y - value
+* @returns sum of products
+*/
+type accumulator = ( x?: number, y?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes a sum of products, ignoring `NaN` values.
+*
+* @returns accumulator function
+*
+* @example
+* var accumulator = incrsumprod();
+*
+* var v = accumulator();
+* // returns null
+*
+* v = accumulator( 2.0, 3.0 );
+* // returns 6.0
+*
+* v = accumulator( -5.0, 2.0 );
+* // returns -4.0
+*
+* v = accumulator( NaN, 6.0 );
+* // returns -4.0
+*
+* v = accumulator();
+* // returns -4.0
+*/
+declare function incrnansumprod(): accumulator;
+
+
+// EXPORTS //
+
+export = incrnansumprod;