diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/README.md b/lib/node_modules/@stdlib/stats/incr/nancv/README.md
new file mode 100644
index 000000000000..8274143bed05
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/README.md
@@ -0,0 +1,207 @@
+
+
+# incrnancv
+
+> Compute the [coefficient of variation][coefficient-of-variation] (CV) incrementally, while ignoring 'NaN' values.
+
+
+
+The [corrected sample standard deviation][sample-stdev] is defined as
+
+
+
+```math
+s = \sqrt{\frac{1}{n-1} \sum_{i=0}^{n-1} ( x_i - \bar{x} )^2}
+```
+
+
+
+
+
+and the [arithmetic mean][arithmetic-mean] is defined as
+
+
+
+```math
+\bar{x} = \frac{1}{n} \sum_{i=0}^{n-1} x_i
+```
+
+
+
+
+
+The [coefficient of variation][coefficient-of-variation] (also known as **relative standard deviation**, RSD) is defined as
+
+
+
+```math
+c_v = \frac{s}{\bar{x}}
+```
+
+
+
+
+
+
+
+
+
+
+
+## Usage
+
+```javascript
+var incrnancv = require( '@stdlib/stats/incr/nancv' );
+```
+
+#### incrnancv( \[mean] )
+
+Returns an accumulator `function` which incrementally computes the [coefficient of variation][coefficient-of-variation], while ignoring 'NaN' value.
+
+```javascript
+var accumulator = incrnancv();
+```
+
+If the mean is already known, provide a `mean` argument.
+
+```javascript
+var accumulator = incrnancv( 3.0 );
+```
+
+#### accumulator( \[x] )
+
+If provided an input value `x`, the accumulator function returns an updated accumulated value. If not provided an input value `x`, the accumulator function returns the current accumulated value.
+
+```javascript
+var accumulator = incrnancv();
+
+var cv = accumulator( 2.0 );
+// returns 0.0
+
+cv = accumulator( 1.0 );
+// returns 0.47140452079103173
+
+cv = accumulator( NaN );
+// returns 0.4714045207910317
+
+cv = accumulator( 3.0 );
+// returns 0.5
+
+cv = accumulator();
+// returns 0.5
+```
+
+
+
+
+
+
+
+## Notes
+
+- Input values are **not** type checked. If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for **all** future invocations.
+- The [coefficient of variation][coefficient-of-variation] is typically computed on nonnegative values. The measure may lack meaning for data which can assume both positive and negative values.
+- For small and moderately sized samples, the accumulated value tends to be too low and is thus a **biased** estimator. Provided the generating distribution is known (e.g., a normal distribution), you may want to adjust the accumulated value or use an alternative implementation providing an unbiased estimator.
+
+
+
+
+
+
+
+## Examples
+
+
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var incrnancv = require( '@stdlib/stats/incr/nancv' );
+
+var accumulator;
+var v;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnancv();
+
+// For each simulated datum, update the coefficient of variation...
+for ( i = 0; i < 100; i++ ) {
+ v = ( (randu() < 0.1) ? NaN : (randu() * 100.0) );
+ accumulator( v );
+}
+console.log( accumulator() );
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+[coefficient-of-variation]: https://en.wikipedia.org/wiki/Coefficient_of_variation
+
+[arithmetic-mean]: https://en.wikipedia.org/wiki/Arithmetic_mean
+
+[sample-stdev]: https://en.wikipedia.org/wiki/Standard_deviation
+
+
+
+[@stdlib/stats/incr/mean]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/mean
+
+[@stdlib/stats/incr/mcv]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/mcv
+
+[@stdlib/stats/incr/stdev]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/stdev
+
+[@stdlib/stats/incr/vmr]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/incr/vmr
+
+
+
+
+
+
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/benchmark/benchmark.js b/lib/node_modules/@stdlib/stats/incr/nancv/benchmark/benchmark.js
new file mode 100644
index 000000000000..a5509bf17cf5
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/benchmark/benchmark.js
@@ -0,0 +1,91 @@
+/**
+* @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 incrnancv = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+ var f;
+ var i;
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ f = incrnancv();
+ 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 = incrnancv();
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ v = acc( randu() );
+ 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();
+});
+
+bench( pkg+'::accumulator,known_mean', function benchmark( b ) {
+ var acc;
+ var v;
+ var i;
+
+ acc = incrnancv( 3.14 );
+
+ b.tic();
+ for ( i = 0; i < b.iterations; i++ ) {
+ v = acc( randu() );
+ 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/nancv/docs/repl.txt b/lib/node_modules/@stdlib/stats/incr/nancv/docs/repl.txt
new file mode 100644
index 000000000000..0ebe3261bc0b
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/docs/repl.txt
@@ -0,0 +1,38 @@
+{{alias}}( [mean] )
+ Returns an accumulator function which incrementally computes the
+ coefficient of variation (CV), ignoring `NaN` values.
+
+ If provided a value, the accumulator function returns an updated
+ accumulated value. If not provided a value, the accumulator function
+ returns the current accumulated value.
+
+ If all received values are `NaN`, the accumulated value remains `null`.
+
+ Parameters
+ ----------
+ mean: number (optional)
+ Known mean.
+
+ Returns
+ -------
+ acc: Function
+ Accumulator function.
+
+ Examples
+ --------
+ > var accumulator = {{alias}}();
+ > var cv = accumulator()
+ null
+ > cv = accumulator( NaN )
+ null
+ > cv = accumulator( 2.0 )
+ 0.0
+ > cv = accumulator( 1.0 )
+ ~0.47
+ > cv = accumulator( NaN )
+ ~0.47
+ > cv = accumulator()
+ ~0.47
+
+ See Also
+ --------
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/index.d.ts b/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/index.d.ts
new file mode 100644
index 000000000000..8f2ef43c8eed
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/index.d.ts
@@ -0,0 +1,67 @@
+/*
+* @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
+
+///
+
+/**
+* If provided a value, the accumulator function returns an updated accumulated value. If not provided a value, the accumulator function returns the current accumulated value.
+*
+* ## Notes
+*
+* - If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for all future invocations.
+*
+* @param x - value
+* @returns accumulated value or null
+*/
+type accumulator = ( x?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes the coefficient of variation (CV), ignoring `NaN` values.
+*
+* @param mean - mean value
+* @returns accumulator function
+*
+* @example
+* var accumulator = incrnancv();
+*
+* var cv = accumulator();
+* // returns null
+*
+* cv = accumulator( 2.0 );
+* // returns 0.0
+*
+* cv = accumulator( 1.0 );
+* // returns ~0.47
+*
+* cv = accumulator( NaN );
+* // returns ~0.47
+*
+* cv = accumulator();
+* // returns ~0.47
+*
+* @example
+* var accumulator = incrnancv( 3.14 );
+*/
+declare function incrnancv( mean?: number ): accumulator;
+
+
+// EXPORTS //
+
+export = incrnancv;
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/test.ts b/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/test.ts
new file mode 100644
index 000000000000..44fe3a4d50f3
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/docs/types/test.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.
+*/
+
+import incrnancv = require( './index' );
+
+
+// TESTS //
+
+// The function returns an accumulator function...
+{
+ incrnancv(); // $ExpectType accumulator
+ incrnancv( 0.0 ); // $ExpectType accumulator
+}
+
+// The compiler throws an error if the function is provided invalid arguments...
+{
+ incrnancv( '5' ); // $ExpectError
+ incrnancv( true ); // $ExpectError
+ incrnancv( false ); // $ExpectError
+ incrnancv( null ); // $ExpectError
+ incrnancv( [] ); // $ExpectError
+ incrnancv( {} ); // $ExpectError
+ incrnancv( ( x: number ): number => x ); // $ExpectError
+}
+
+// The function returns an accumulator function which returns an accumulated result...
+{
+ const acc = incrnancv();
+
+ 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 = incrnancv();
+
+ 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/nancv/examples/index.js b/lib/node_modules/@stdlib/stats/incr/nancv/examples/index.js
new file mode 100644
index 000000000000..e15dd209e030
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/examples/index.js
@@ -0,0 +1,39 @@
+/**
+* @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';
+
+var randu = require( '@stdlib/random/base/randu' );
+var incrnancv = require( './../lib' );
+
+var accumulator;
+var cv;
+var v;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnancv();
+
+// For each simulated datum, update the coefficient of variation, ignoring NaN values...
+console.log( '\nValue\tCV\n' );
+for ( i = 0; i < 100; i++ ) {
+ v = ( (randu() < 0.1) ? NaN : (randu() * 100.0) );
+ cv = accumulator( v );
+ console.log( '%d\t%d', v.toFixed( 4 ), cv.toFixed( 4 ) );
+}
+console.log( '\nFinal CV: %d\n', accumulator() );
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/lib/index.js b/lib/node_modules/@stdlib/stats/incr/nancv/lib/index.js
new file mode 100644
index 000000000000..b7078cfde7fe
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/lib/index.js
@@ -0,0 +1,54 @@
+/**
+* @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';
+
+/**
+* Compute the coefficient of variation (CV) incrementally, ignoring `NaN` values.
+*
+* @module @stdlib/stats/incr/nancv
+*
+* @example
+* var incrnancv = require( '@stdlib/stats/incr/nancv' );
+*
+* var accumulator = incrnancv();
+*
+* var cv = accumulator();
+* // returns null
+*
+* cv = accumulator( 2.0 );
+* // returns 0.0
+*
+* cv = accumulator( NaN );
+* // returns 0.0
+*
+* cv = accumulator( 1.0 );
+* // returns ~0.47
+*
+* cv = accumulator();
+* // returns ~0.47
+*/
+
+// MODULES //
+
+var main = require( './main.js' );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/lib/main.js b/lib/node_modules/@stdlib/stats/incr/nancv/lib/main.js
new file mode 100644
index 000000000000..85e21d8d2756
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/lib/main.js
@@ -0,0 +1,79 @@
+/**
+* @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 incrcv = require( '@stdlib/stats/incr/cv' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
+// MAIN //
+
+/**
+* Returns an accumulator function which incrementally computes the coefficient of variation (CV), ignoring NaN values.
+*
+* @returns {Function} accumulator function
+*
+* @example
+* var accumulator = incrnancv();
+*
+* var cv = accumulator();
+* // returns null
+*
+* cv = accumulator( 2.0 );
+* // returns 0.0
+*
+* cv = accumulator( NaN );
+* // returns 0.0
+*
+* cv = accumulator( 1.0 );
+* // returns ~0.47
+*
+* cv = accumulator();
+* // returns ~0.47
+*/
+function incrnancv() {
+ var cv = incrcv();
+
+ /**
+ * If provided a value, the accumulator function returns an updated accumulated value.
+ * If not provided a value, the accumulator function returns the current accumulated value.
+ *
+ * @private
+ * @param {number} [x] - new value
+ * @returns {(number|null)} accumulated value or null
+ */
+ function accumulator( x ) {
+ if ( arguments.length === 0 ) {
+ return cv();
+ }
+ if ( isnan( x ) ) {
+ return cv();
+ }
+ return cv( x );
+ }
+
+ return accumulator;
+}
+
+
+// EXPORTS //
+
+module.exports = incrnancv;
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/package.json b/lib/node_modules/@stdlib/stats/incr/nancv/package.json
new file mode 100644
index 000000000000..0f920daf9823
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/package.json
@@ -0,0 +1,73 @@
+{
+ "name": "@stdlib/stats/incr/nancv",
+ "version": "0.0.0",
+ "description": "Compute the coefficient of variation (CV) incrementally.",
+ "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",
+ "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",
+ "stdev",
+ "std",
+ "variance",
+ "var",
+ "standard",
+ "deviation",
+ "dispersion",
+ "relative",
+ "rsd",
+ "cv",
+ "mean",
+ "ratio",
+ "incremental",
+ "accumulator"
+ ]
+}
diff --git a/lib/node_modules/@stdlib/stats/incr/nancv/test/test.js b/lib/node_modules/@stdlib/stats/incr/nancv/test/test.js
new file mode 100644
index 000000000000..e01019857f84
--- /dev/null
+++ b/lib/node_modules/@stdlib/stats/incr/nancv/test/test.js
@@ -0,0 +1,226 @@
+/**
+* @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 tape = require( 'tape' );
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var sqrt = require( '@stdlib/math/base/special/sqrt' );
+var incrnancv = require( './../lib' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+ t.ok( true, __filename );
+ t.strictEqual( typeof incrnancv, 'function', 'main export is a function' );
+ t.end();
+});
+
+tape( 'the function returns an accumulator function', function test( t ) {
+ t.equal( typeof incrnancv(), 'function', 'returns a function' );
+ t.end();
+});
+
+tape( 'the function returns an accumulator function (known mean)', function test( t ) {
+ t.equal( typeof incrnancv( 3.0 ), 'function', 'returns a function' );
+ t.end();
+});
+
+tape( 'the accumulator function incrementally computes the coefficient of variation while ignoring NaN values', function test( t ) {
+ var expected;
+ var actual = [];
+ var data;
+ var acc;
+ var i;
+
+ data = [ 2.0, NaN, 3.0, 2.0, 4.0, NaN, 3.0, 4.0 ];
+
+ // Expected values ignoring NaNs:
+ expected = [
+ 0.0 / (2.0 / 1.0),
+ 0.0 / (2.0 / 1.0), // NaN ignored
+ sqrt( 0.5 ) / (5.0 / 2.0),
+ sqrt( 0.33333333333333337 ) / (7.0 / 3.0),
+ sqrt( 0.9166666666666666 ) / (11.0 / 4.0),
+ sqrt( 0.9166666666666666 ) / (11.0 / 4.0), // NaN ignored
+ sqrt( 0.7 ) / (14.0 / 5.0),
+ sqrt( 0.8 ) / (18.0 / 6.0)
+ ];
+
+ acc = incrnancv();
+
+ for ( i = 0; i < data.length; i++ ) {
+ actual.push( acc( data[ i ] ) );
+ }
+ t.deepEqual( actual, expected, 'returns expected results' );
+ t.end();
+});
+
+tape( 'if not provided an input value, the accumulator function returns the current accumulated value', function test( t ) {
+ var data;
+ var acc;
+ var i;
+
+ data = [ 2.0, NaN, 3.0, 1.0 ];
+ acc = incrnancv();
+ for ( i = 0; i < data.length; i++ ) {
+ acc( data[ i ] );
+ }
+ t.equal( acc(), sqrt( 1.0 ) / 2.0, 'returns expected value' );
+ t.end();
+});
+
+tape( 'if not provided an input value, the accumulator function returns the current accumulated value (known mean, ignoring NaNs)', function test( t ) {
+ var data;
+ var acc;
+ var i;
+
+ data = [ 2.0, NaN, 3.0, 1.0, NaN ];
+ acc = incrnancv( 2.0 );
+
+ for ( i = 0; i < data.length; i++ ) {
+ acc( data[ i ] );
+ }
+
+ t.equal( acc(), 0.5, 'returns expected value while ignoring NaNs' );
+ t.end();
+});
+
+tape( 'the accumulated value is `null` until at least 1 valid datum has been provided (unknown mean, ignoring NaNs)', function test( t ) {
+ var acc;
+ var cv;
+
+ acc = incrnancv();
+
+ cv = acc();
+ t.equal( cv, null, 'returns null' );
+
+ cv = acc( NaN );
+ t.equal( cv, null, 'still returns null after NaN' );
+
+ cv = acc( 3.0 );
+ t.notEqual( cv, null, 'does not return null after valid number' );
+
+ cv = acc();
+ t.notEqual( cv, null, 'does not return null' );
+
+ t.end();
+});
+
+tape( 'the accumulated value is `null` until at least 1 valid datum has been provided (known mean, ignoring NaNs)', function test( t ) {
+ var acc;
+ var cv;
+
+ acc = incrnancv( 3.0 );
+
+ cv = acc();
+ t.equal( cv, null, 'returns null' );
+
+ cv = acc( NaN );
+ t.equal( cv, null, 'still returns null after NaN' );
+
+ cv = acc( 3.0 );
+ t.notEqual( cv, null, 'does not return null after valid number' );
+
+ cv = acc();
+ t.notEqual( cv, null, 'does not return null' );
+
+ t.end();
+});
+
+tape( 'the accumulated value is `null` until at least 1 non-NaN datum has been provided', function test( t ) {
+ var acc;
+ var cv;
+
+ acc = incrnancv();
+
+ cv = acc();
+ t.equal( cv, null, 'returns null' );
+
+ cv = acc( NaN );
+ t.equal( cv, null, 'returns null' );
+
+ cv = acc( 3.0 );
+ t.notEqual( cv, null, 'does not return null' );
+
+ cv = acc();
+ t.notEqual( cv, null, 'does not return null' );
+
+ t.end();
+});
+
+tape( 'the accumulated value is `0` until at least 2 valid datums have been provided (unknown mean, ignoring NaNs)', function test( t ) {
+ var acc;
+ var cv;
+
+ acc = incrnancv();
+
+ cv = acc( 2.0 );
+ t.equal( cv, 0.0, 'returns 0' );
+
+ cv = acc();
+ t.equal( cv, 0.0, 'returns 0' );
+
+ cv = acc( NaN );
+ t.equal( cv, 0.0, 'still returns 0 after NaN' );
+
+ cv = acc( 3.0 );
+ t.notEqual( cv, 0.0, 'does not return 0 after two valid numbers' );
+
+ cv = acc();
+ t.notEqual( cv, 0.0, 'does not return 0' );
+
+ t.end();
+});
+
+tape( 'if provided a `NaN`, the accumulator function ignores it and continues accumulating valid values (unknown mean)', function test( t ) {
+ var data;
+ var acc;
+ var v;
+ var i;
+
+ data = [ 2.0, NaN, 1.0, NaN, 2.0, 3.0, NaN, 4.0, 5.0, 6.0, 7.0 ];
+ acc = incrnancv();
+ for ( i = 0; i < data.length; i++ ) {
+ v = acc( data[ i ] );
+ t.notEqual( isnan( v ), true, 'does not return NaN' );
+ t.notEqual( isnan( acc() ), true, 'does not return NaN' );
+ }
+ t.notEqual( isnan( acc() ), true, 'does not return NaN' );
+ t.end();
+});
+
+tape( 'if provided a `NaN`, the accumulator function ignores it and continues accumulating valid values (known mean)', function test( t ) {
+ var data;
+ var acc;
+ var v;
+ var i;
+
+ data = [ 2.0, NaN, 1.0, NaN, 2.0, 3.0, NaN, 4.0, 5.0, 6.0, 7.0 ];
+ acc = incrnancv( 3.14 );
+ for ( i = 0; i < data.length; i++ ) {
+ v = acc( data[ i ] );
+ t.notEqual( isnan( v ), true, 'does not return NaN' );
+ t.notEqual( isnan( acc() ), true, 'does not return NaN' );
+ }
+ t.notEqual( isnan( acc() ), true, 'does not return NaN' );
+ t.end();
+});