191 lines
3.7 KiB
Markdown
191 lines
3.7 KiB
Markdown
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<!--
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@license Apache-2.0
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Copyright (c) 2020 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# invf
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> Compute the [multiplicative inverse][multiplicative-inverse] of a single-precision floating-point number.
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<section class="intro">
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The [multiplicative inverse][multiplicative-inverse] (or **reciprocal**) is defined as
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<!-- <equation class="equation" label="eq:multiplicative_inverse" align="center" raw="y = \frac{1}{x}" alt="Multiplicative inverse"> -->
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<div class="equation" align="center" data-raw-text="y = \frac{1}{x}" data-equation="eq:multiplicative_inverse">
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<img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@11a2410024c2ba7d3681e2c6d6ee91859fc32a28/lib/node_modules/@stdlib/math/base/special/invf/docs/img/equation_multiplicative_inverse.svg" alt="Multiplicative inverse">
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<br>
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</div>
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<!-- </equation> -->
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</section>
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<!-- /.intro -->
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<section class="usage">
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## Usage
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```javascript
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var invf = require( '@stdlib/math/base/special/invf' );
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```
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#### invf( x )
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Computes the [multiplicative inverse][multiplicative-inverse] of a single-precision floating-point number `x`.
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```javascript
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var v = invf( -1.0 );
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// returns -1.0
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v = invf( 2.0 );
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// returns 0.5
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v = invf( 0.0 );
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// returns Infinity
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v = invf( -0.0 );
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// returns -Infinity
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v = invf( NaN );
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// returns NaN
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var randu = require( '@stdlib/random/base/randu' );
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var round = require( '@stdlib/math/base/special/round' );
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var invf = require( '@stdlib/math/base/special/invf' );
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var x;
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var i;
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for ( i = 0; i < 100; i++ ) {
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x = round( randu()*100.0 ) - 50.0;
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console.log( 'invf(%d) = %d', x, invf( x ) );
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}
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```
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</section>
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<!-- /.examples -->
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<!-- C interface documentation. -->
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* * *
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<section class="c">
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## C APIs
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<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
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<section class="intro">
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</section>
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<!-- /.intro -->
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<!-- C usage documentation. -->
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<section class="usage">
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### Usage
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```c
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#include "stdlib/math/base/special/invf.h"
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```
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#### stdlib_base_invf( x )
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Computes the multiplicative inverse of a single-precision floating-point number.
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```c
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float y = stdlib_base_invf( 2.0f );
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// returns 0.5f
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```
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The function accepts the following arguments:
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- **x**: `[in] float` input value.
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```c
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float stdlib_base_inv( const float x );
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```
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</section>
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<!-- /.usage -->
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<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
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<section class="notes">
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</section>
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<!-- /.notes -->
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<!-- C API usage examples. -->
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<section class="examples">
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### Examples
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```c
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#include "stdlib/math/base/special/invf.h"
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#include <stdio.h>
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int main() {
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float x[] = { 3.0f, 4.0f, 5.0f, 12.0f };
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float y;
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int i;
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for ( i = 0; i < 4; i++ ) {
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y = stdlib_base_invf( x[ i ] );
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printf( "inv(%f) = %f\n", x[ i ], y );
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}
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}
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```
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</section>
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<!-- /.examples -->
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</section>
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<!-- /.c -->
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<section class="links">
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[multiplicative-inverse]: https://en.wikipedia.org/wiki/Multiplicative_inverse
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</section>
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<!-- /.links -->
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