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314 changes: 314 additions & 0 deletions lib/node_modules/@stdlib/stats/strided/snanmeankbn/README.md
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<!--

@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.

-->

# snanmeankbn

> Calculate the [arithmetic mean][arithmetic-mean] of a single-precision floating-point strided array ignoring `NaN` values and using an improved Kahan-Babuska algorithm.

<section class="intro">

The [arithmetic mean][arithmetic-mean] is defined as

<!-- <equation class="equation" label="eq:arithmetic_mean" align="center" raw="\mu = \frac{1}{n} \sum_{i=0}^{n-1} x_i" alt="Equation for the arithmetic mean."> -->

```math
\mu = \frac{1}{n} \sum_{i=0}^{n-1} x_i
```

<!-- <div class="equation" align="center" data-raw-text="\mu = \frac{1}{n} \sum_{i=0}^{n-1} x_i" data-equation="eq:arithmetic_mean">
<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@60af5c459896bb85413697508c87c6a069a60e57/lib/node_modules/@stdlib/stats/strided/snanmeankbn/docs/img/equation_arithmetic_mean.svg" alt="Equation for the arithmetic mean.">
<br>
</div> -->

<!-- </equation> -->

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var snanmeankbn = require( '@stdlib/stats/strided/snanmeankbn' );
```

#### snanmeankbn( N, x, strideX )

Calculate the [arithmetic mean][arithmetic-mean] of a single-precision floating-point strided array ignoring `NaN` values and using an improved Kahan-Babuska algorithm.

```javascript
var Float32Array = require( '@stdlib/array/float32' );

var x = new Float32Array( [ 1.0, -2.0, NaN, 2.0 ] );

var v = snanmeankbn( x.length, x, 1 );
// returns ~0.3333
```

The function has the following parameters:

- **N**: number of indexed elements.
- **x**: input [`Float32Array`][@stdlib/array/float32].
- **strideX**: stride length.

The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the [arithmetic mean][arithmetic-mean] of every other element in `x`,

```javascript
var Float32Array = require( '@stdlib/array/float32' );

var x = new Float32Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0, NaN ] );

var v = snanmeankbn( 4, x, 2 );
// returns 1.25
```

Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.

<!-- eslint-disable stdlib/capitalized-comments, max-len -->

```javascript
var Float32Array = require( '@stdlib/array/float32' );

var x0 = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN, NaN ] );
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = snanmeankbn( 5, x1, 2 );
// returns 1.25
```

#### snanmeankbn.ndarray( N, x, strideX, offsetX )

Computes the [arithmetic mean][arithmetic-mean] of a single-precision floating-point strided array ignoring `NaN` values and using an improved Kahan-Babuska algorithm and alternative indexing semantics.

```javascript
var Float32Array = require( '@stdlib/array/float32' );

var x = new Float32Array( [ 1.0, -2.0, NaN, 2.0 ] );

var v = snanmeankbn.ndarray( x.length, x, 1, 0 );
// returns ~0.33333
```

The function has the following additional parameters:

- **offsetX**: starting index.

While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to calculate the [arithmetic mean][arithmetic-mean] for every other element in `x` starting from the second element

<!-- eslint-disable max-len -->

```javascript
var Float32Array = require( '@stdlib/array/float32' );

var x = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN, NaN ] );

var v = snanmeankbn.ndarray( 5, x, 2, 1 );
// returns 1.25
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

- If `N <= 0`, both functions return `NaN`.
- If every indexed element is `NaN`, both functions return `NaN`.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var uniform = require( '@stdlib/random/base/uniform' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var bernoulli = require( '@stdlib/random/base/bernoulli' );
var snanmeankbn = require( '@stdlib/stats/strided/snanmeankbn' );

function rand() {
if ( bernoulli( 0.8 ) < 1 ) {
return NaN;
}
return uniform( -50.0, 50.0 );
}

var x = filledarrayBy( 10, 'float32', rand );
console.log( x );

var v = snanmeankbn( x.length, x, 1 );
console.log( v );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/stats/strided/snanmeankbn.h"
```

#### stdlib_strided_snanmeankbn( N, \*X, strideX )

Calculate the [arithmetic mean][arithmetic-mean] of a single-precision floating-point strided array ignoring `NaN` values and using an improved Kahan-Babuska algorithm.

```c
const float x[] = { 1.0f, 2.0f, 3.0f, 0.0f/0.0f };

float v = stdlib_strided_snanmeankbn( 4, x, 1 );
// returns 2.0f
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **X**: `[in] float*` input array.
- **strideX**: `[in] CBLAS_INT` stride length.

```c
float stdlib_strided_snanmeankbn( const CBLAS_INT N, const float *X, const CBLAS_INT strideX );
```

#### stdlib_strided_snanmeankbn_ndarray( N, \*X, strideX, offsetX )

Computes the [arithmetic mean][arithmetic-mean] of a single-precision floating-point strided array ignoring `NaN` values and using an improved Kahan-Babuska algorithm and alternative indexing semantics.

```c
const float x[] = { 1.0f, 2.0f, 3.0f, 0.0f/0.0f };

float v = stdlib_strided_snanmeankbn_ndarray( 4, x, 1, 0 );
// returns 2.0f
```

The function accepts the following arguments:

- **N**: `[in] CBLAS_INT` number of indexed elements.
- **X**: `[in] float*` input array.
- **strideX**: `[in] CBLAS_INT` stride length.
- **offsetX**: `[in] CBLAS_INT` starting index.

```c
float stdlib_strided_snanmeankbn_ndarray( const CBLAS_INT N, const float *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/stats/strided/snanmeankbn.h"
#include <stdio.h>

int main( void ) {
// Create a strided array:
const float x[] = { 1.0f, 2.0f, 0.0f/0.0f, 3.0f, 0.0f/0.0f, 4.0f, 5.0f, 6.0f, 0.0f/0.0f, 7.0f, 8.0f, 0.0f/0.0f };

// Specify the number of elements:
const int N = 6;

// Specify the stride length:
const int strideX = 2;

// Compute the arithmetic mean:
float v = stdlib_strided_snanmeankbn( N, x, strideX );

// Print the result:
printf( "mean: %f\n", v );
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</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">

[arithmetic-mean]: https://en.wikipedia.org/wiki/Arithmetic_mean

[@stdlib/array/float32]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/float32

[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray

<!-- <related-links> -->

<!-- </related-links> -->

</section>

<!-- /.links -->
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