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

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

• Evaluate 2 + 3 - 5

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