roc-rs

Rate Of Change (ROC) implementation in rust ``` use rocrs::ROC; use tacommon::traits::Indicator;

let mut roc = ROC::new(1, None); let res = roc.next(100 as f64); asserteq!(None, res); let res = roc.next(50 as f64); asserteq!(Some(-50_f32), res);

```

Calculation

ROCR=(Current Price/Price Prev n Ago);
ROCP=ROCR-1;
ROC100=(ROCR)100;
ROC=(ROCR-1)100; //DEFAULT