exp4j

# Built in Operators

There are three basic sets of operators available:

## Arithmetic

All of the arithmetic operators are included and available: `+`, `-`, `*`, `/`

and of course `%` (modulo).

## Boolean

Boolean operators will consider `false` every value equal to zero ([`0 ± 0.000000000001`](https://gitlab.com/riddler_arg/exp4j/blob/master/src/main/java/net/objecthunter/exp4j/operator/Operator.java#L70)), and `true` every other value. 

But they are warrantied to return `1.0` for `true` and `0.0` for `false`. The

available operators are: `&` (and), `|` (or), `¬` (not).

There are also a set of [[Extra Functions|Extra Functions and Operators]]

## Precedence

For those who don't know, precedence of operators refers to which of the

operators will be evaluated first when left alone. I won't bother you with

numbers, the order of evaluation is as follows:

```

FIRST->  * / %  - +  ¬  &  |  == !=   <-LAST

         -----  ---  -  -  -  -----    

         ^^^ The dashes indicate groups with the same precedence

```

When operators have the same precedence they will be evaluated from left to

right.

***Note:*** as in primary school (and beyond) you can always alter the

precedence of operators with the use of parentheses.

## Factorial

Factorial isn't technically an operator... it's a function but since it's so common, it's implemented by using the `!` symbol and with more precedence than the arithmetic multiplication. Even though the implementation of operators is trivial in `exp4j` the factorial is the only postfix unary operator, so it deserves a [special case](https://gitlab.com/riddler_arg/exp4j/blob/master/src/main/java/net/objecthunter/exp4j/operator/Operators.java#L183).

**Note:** Factorials from `0!` to `21!` are guaranteed to be correct, bigger than `21!` may suffer lost of precision because of `double` rounding.

**Note 2:** Factorials bigger than `170!` will rise an `IllegalArgumentException` since the value will be `Double.INFINITY`.

## Code

The code for the operators is [here](https://gitlab.com/riddler_arg/exp4j/blob/master/src/main/java/net/objecthunter/exp4j/operator/Operators.java).