Funciones y Operadores adicionales » Histórico » Versión 2
Federico Vera, 2018-07-12 17:41
1 | 1 | Federico Vera | # Funciones y Operadores adicionales |
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3 | {{>toc}} |
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5 | There are a number of extra functions and operators included in this version of `exp4j`, non of this are enabled by default, they are in the [`net.objecthunter.exp4j.extras`](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/show/src/main/java/net/objecthunter/exp4j/extras) package. |
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7 | ## Comparison Operators |
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8 | Aside from the arithmetic operators several comparison operators are included: `<`, `<=`, `>`, `>=`, `!=` and `==`. |
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9 | Please note that since `exp4j` itself has no concept of `boolean`, the results given by all of the comparison operators will be `1.0` if `true` and `0.0` if `false`. Let it be noted that due to rounding, equality operators use a radix in which they consider numbers to be "equal", that is: |
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11 | Let `a` and `b` be two real numbers, `a == b` will evaluate to `true` if and only if the distance between `a` and `b` (`dist(a, b) := abs(a - b)`) is less or equal than [`1e-12` (`0.000000000001`)](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/extras/FunctionsMisc.java#L38) and `false` otherwise. |
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13 | ### Precedence |
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14 | Operator precedence is altered when using the comparison operators, the new precedence is: |
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15 | ~~~ |
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16 | FIRST-> * / % - + > >= < <= ¬ & | == != <-LAST |
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17 | ----- --- --------- - - - ----- |
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18 | ^^^ The dashes indicate groups with the same precedence |
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19 | ~~~ |
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21 | ## Funciones lógicas |
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22 | Even though we have boolean operators, there are also a number of boolean functions that can be used (some people prefer functions) |
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23 | * `and(a, b)`: Y lógico _equivalente a `a & b`_ |
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24 | * `or(a, b)`: O lógico _equivalente a `a | b`_ |
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25 | * `xor(a, b)`: O exclusivo |
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26 | * `nand(a, b)`: _equivalente a `¬(a & b)`_ |
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27 | * `nor(a, b)`: _equivalente a `¬(a | b)`_ |
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28 | * `xnor(a, b)`: O exclusivo negado |
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29 | * `not(a)`: _equivalente a `¬a`_ |
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31 | ## Constantes lógicas |
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32 | * `true()`: verdadero (`1.0`) (se considera como verdadero a cualquier valor distinto de cero, pero la función `true()` devuelve `1.0` así como los operadores booleans y de comparación. |
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33 | * `false()`: falso (`0.0`) |
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35 | 2 | Federico Vera | ## Funciones adicionales |
36 | * `if(e, v_true, v_false)`: Ramifica la expresión, se evalúa como `v_true` si `e == true()` y `v_false` si `e == false()` |
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37 | * `equals(a, b)`: Equivalente a `a == b`, por lo tanto se cumplen las mismas condiciones. |
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38 | * `sinc(x)`: [Seno cardinal de `x`](https://en.wikipedia.org/wiki/Sinc_function) (no normalizado), equivalente a `sin(x)/x` |
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39 | 1 | Federico Vera | |
40 | 2 | Federico Vera | ## Código |
41 | 1 | Federico Vera | El código está [aquí](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/extras/OperatorsComparison.java), [aquí](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/extras/FunctionsMisc.java) u [aquí](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/extras/FunctionsBoolean.java). |