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feat: add math/base/tools/normhermitepolyf
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PR-URL: 	#2151
Closes: #2029
Co-authored-by: Athan Reines <kgryte@gmail.com>
Reviewed-by: Athan Reines <kgryte@gmail.com>
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Daniel777y and kgryte committed Apr 20, 2024
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181 changes: 181 additions & 0 deletions lib/node_modules/@stdlib/math/base/tools/normhermitepolyf/README.md
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<!--
@license Apache-2.0
Copyright (c) 2024 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.
-->

# Normalized Hermite Polynomial

> Evaluate a normalized [Hermite polynomial][hermite-polynomial] using single-precision floating-point arithmetic.
<!-- 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">

The normalized (aka "probabilist") [Hermite polynomials][hermite-polynomial] are given by

<!-- <equation class="equation" label="eq:normalized_hermite_polynomials" align="center" raw="He_{n}(x)=(-1)^{n} e^{\frac{x^2}{2}} \frac{\mathrm d^{n}}{\mathrm d x^{n}} e^{-\frac{x^2}{2}}" alt="Equation for normalized Hermite polynomials."> -->

```math
He_{n}(x)=(-1)^{n} e^{\frac{x^2}{2}} \frac{\mathrm d^{n}}{\mathrm d x^{n}} e^{-\frac{x^2}{2}}
```

<!-- <div class="equation" align="center" data-raw-text="He_{n}(x)=(-1)^{n} e^{\frac{x^2}{2}} \frac{\mathrm{d}^{n}}{\mathrm{d}x^n} e^{-\frac{x^2}{2}}" data-equation="eq:normalized_hermite_polynomials">
<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@bea0101eb61892f160eec8d97dc79188fd937523/lib/node_modules/@stdlib/math/base/tools/normhermitepoly/docs/img/equation_normalized_hermite_polynomials.svg" alt="Equation for normalized Hermite polynomials.">
<br>
</div> -->

<!-- </equation> -->

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var normhermitepolyf = require( '@stdlib/math/base/tools/normhermitepolyf' );
```

#### normhermitepolyf( n, x )

Evaluates a normalized [Hermite polynomial][hermite-polynomial] of degree `n` using single-precision floating-point arithmetic.

```javascript
var v = normhermitepolyf( 1, 1.0 );
// returns 1.0

v = normhermitepolyf( 1, 0.5 );
// returns 0.5

v = normhermitepolyf( 0, 0.5 );
// returns 1.0

v = normhermitepolyf( 2, 0.5 );
// returns -0.75

v = normhermitepolyf( -1, 0.5 );
// returns NaN
```

#### normhermitepolyf.factory( n )

Returns a function for evaluating a normalized [Hermite polynomial][hermite-polynomial] of degree `n` using single-precision floating-point arithmetic.

```javascript
var polyval = normhermitepolyf.factory( 2 );

var v = polyval( 0.5 );
// returns -0.75
```

</section>

<!-- /.usage -->

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

<section class="notes">

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var uniform = require( '@stdlib/random/array/uniform' );
var zeros = require( '@stdlib/array/zeros' );
var smap = require( '@stdlib/strided/base/smap' );
var logEach = require( '@stdlib/console/log-each' );
var normhermitepolyf = require( '@stdlib/math/base/tools/normhermitepolyf' );

// Generate random values at which to evaluate a polynomial:
var x = uniform( 10, -50.0, 50.0, {
'dtype': 'float32'
});

// Create a polynomial function of degree 1:
var f = normhermitepolyf.factory( 1 );

// Allocate an output array:
var y = zeros( x.length, 'float32' );

// Evaluate the polynomial:
smap( x.length, x, 1, y, 1, f );
logEach( 'He_%d(%.3f) = %.3f', 1, x, y );

// Create a polynomial function of degree 2:
f = normhermitepolyf.factory( 2 );

// Allocate an output array:
y = zeros( x.length, 'float32' );

// Evaluate the polynomial:
smap( x.length, x, 1, y, 1, f );
logEach( 'He_%d(%.3f) = %.3f', 2, x, y );

// Create a polynomial function of degree 3:
f = normhermitepolyf.factory( 3 );

// Allocate an output array:
y = zeros( x.length, 'float32' );

// Evaluate the polynomial:
smap( x.length, x, 1, y, 1, f );
logEach( 'He_%d(%.3f) = %.3f', 3, x, y );
```

</section>

<!-- /.examples -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- 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">

[hermite-polynomial]: https://en.wikipedia.org/wiki/Hermite_polynomials

</section>

<!-- /.links -->
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/**
* @license Apache-2.0
*
* Copyright (c) 2024 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 uniform = require( '@stdlib/random/array/uniform' );
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
var pkg = require( './../package.json' ).name;
var factory = require( './../lib/factory.js' );


// MAIN //

bench( pkg+'::create:factory', function benchmark( b ) {
var n;
var f;
var i;

n = discreteUniform( 10, 1, 10, {
'dtype': 'float32'
});

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
f = factory( n[ i%n.length ] );
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+'::evaluate:factory', function benchmark( b ) {
var x;
var v;
var f;
var i;

f = factory( 2 );
x = uniform( 10, -5.0, 5.0, {
'dtype': 'float32'
});

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
v = f( x[ i%x.length ] );
if ( isnanf( v ) ) {
b.fail( 'should not return NaN' );
}
}
b.toc();
if ( isnanf( v ) ) {
b.fail( 'should not return NaN' );
}
b.pass( 'benchmark finished' );
b.end();
});
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/**
* @license Apache-2.0
*
* Copyright (c) 2024 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 uniform = require( '@stdlib/random/array/uniform' );
var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
var pkg = require( './../package.json' ).name;
var normhermitepolyf = require( './../lib' );


// MAIN //

bench( pkg, function benchmark( b ) {
var opts;
var x;
var y;
var i;

opts = {
'dtype': 'float32'
};
x = uniform( 10, -5.0, 5.0, opts );

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
y = normhermitepolyf( 2, x[ i%x.length ] );
if ( isnanf( y ) ) {
b.fail( 'should not return NaN' );
}
}
b.toc();
if ( isnanf( y ) ) {
b.fail( 'should not return NaN' );
}
b.pass( 'benchmark finished' );
b.end();
});

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Coverage Report

Package Statements Branches Functions Lines
math/base/tools/normhermitepolyf $\color{green}230/230$
$\color{green}+100.00\%$
$\color{green}27/27$
$\color{green}+100.00\%$
$\color{green}3/3$
$\color{green}+100.00\%$
$\color{green}230/230$
$\color{green}+100.00\%$

The above coverage report was generated for the changes in this push.

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