# polishexpr

A poorly implemented polish reverse expression evaluator.

The list of supported functions are:

* **Arithmetic functions**: +, -, *, /
* **sin**: sine
* **cos**: cosine
* **ln**: natural logarithm
* **exp**: exponent
* **sqrt**: square root

Arguments for these functions could be as usual constants, written as numbers,
as variables, written as $var_number ($0, for example). The variable number
is zero based index of variables vector.

## Usage

* Sums 2+2 and equals 4

```rust
let pe = PolishEvaluator::new("$0 2 +", &[2.0]);
let result = pe.evaluate()?;
assert_eq!(4f64, result);
```

* Evaluate 2 + 3 - 5

```rust
let pe = PolishEvaluator::new("$0 $1 + $3 -", &[2.0, 3.0, 5.0]);
let result = pe.evaluate()?;
assert_eq!(0f64, result);
```