time-to-botec

Benchmark sampling in different programming languages
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README.md (2961B)

      1 <!--
      2 
      3 @license Apache-2.0
      4 
      5 Copyright (c) 2018 The Stdlib Authors.
      6 
      7 Licensed under the Apache License, Version 2.0 (the "License");
      8 you may not use this file except in compliance with the License.
      9 You may obtain a copy of the License at
     10 
     11    http://www.apache.org/licenses/LICENSE-2.0
     12 
     13 Unless required by applicable law or agreed to in writing, software
     14 distributed under the License is distributed on an "AS IS" BASIS,
     15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     16 See the License for the specific language governing permissions and
     17 limitations under the License.
     18 
     19 -->
     20 
     21 # isUnityProbabilityArray
     22 
     23 > Test if a value is an array of probabilities that sum to one.
     24 
     25 <section class="usage">
     26 
     27 ## Usage
     28 
     29 ```javascript
     30 var isUnityProbabilityArray = require( '@stdlib/assert/is-unity-probability-array' );
     31 ```
     32 
     33 #### isUnityProbabilityArray( value )
     34 
     35 Tests if a `value` is an array of probabilities that sum to one.
     36 
     37 ```javascript
     38 var Uint8Array = require( '@stdlib/array/uint8' );
     39 
     40 var bool = isUnityProbabilityArray( [ 0.25, 0.5, 0.25 ] );
     41 // returns true
     42 
     43 bool = isUnityProbabilityArray( new Uint8Array( [ 0, 1 ] ) );
     44 // returns true
     45 
     46 bool = isUnityProbabilityArray( [ 3.14, 0.0 ] );
     47 // returns false
     48 ```
     49 
     50 </section>
     51 
     52 <!-- /.usage -->
     53 
     54 <section class="notes">
     55 
     56 ## Notes
     57 
     58 -   Summation of finite-precision floating-point numbers often has numerical error. For example,
     59 
     60     ```javascript
     61     var arr = [ 0.1, 0.2, 0.1, 0.1, 0.2, 0.2, 0.1 ]; // => 1.0
     62     var sum = 0.0;
     63     var i;
     64     for ( i = 0; i < arr.length; i++ ) {
     65         sum += arr[ i ];
     66     }
     67     console.log( sum );
     68     // => 0.9999999999999999
     69     ```
     70 
     71     To account for numerical error, the function tests if array elements sum to approximately one; specifically,
     72 
     73     ```text
     74     1.0 - sqrt(eps) <= sum(A) <= 1.0 + sqrt(eps)
     75     ```
     76 
     77     where `eps` is [double-precision floating-point][ieee754] epsilon (`~2.22e-16`) and `sqrt(eps) ~ 1.49e-8`. The above comparison ensures equality for approximately half the significand bits.
     78 
     79 </section>
     80 
     81 <!-- /.notes -->
     82 
     83 <section class="examples">
     84 
     85 ## Examples
     86 
     87 <!-- eslint no-undef: "error" -->
     88 
     89 ```javascript
     90 var Uint8Array = require( '@stdlib/array/uint8' );
     91 var isUnityProbabilityArray = require( '@stdlib/assert/is-unity-probability-array' );
     92 
     93 var arr = [ 0.0, 1.0 ];
     94 var bool = isUnityProbabilityArray( arr );
     95 // returns true
     96 
     97 arr = [ 0.5, 0.25, 0.25 ];
     98 bool = isUnityProbabilityArray( arr );
     99 // returns true
    100 
    101 arr = new Uint8Array( [ 0, 0, 1, 0 ] );
    102 bool = isUnityProbabilityArray( arr );
    103 // returns true
    104 
    105 arr = [ 0.4, 0.4, 0.4 ];
    106 bool = isUnityProbabilityArray( arr );
    107 // returns false
    108 
    109 arr = [ 3.14, -1.0 ];
    110 bool = isUnityProbabilityArray( arr );
    111 // returns false
    112 
    113 bool = isUnityProbabilityArray( [] );
    114 // returns false
    115 
    116 bool = isUnityProbabilityArray( null );
    117 // returns false
    118 ```
    119 
    120 </section>
    121 
    122 <!-- /.examples -->
    123 
    124 <section class="links">
    125 
    126 [ieee754]: https://en.wikipedia.org/wiki/IEEE_floating_point
    127 
    128 </section>
    129 
    130 <!-- /.links -->