You may or may not know that NinjaTrader’s ROC indicator calculates the ROC only in percentage, not in points. I wasn’t (and I blame the Help Guide for not pointing it out clearly 
). I didn’t find it out until I looked at the source code in the NinjaScript Editor after much frustration. Therefore, my bonus tip (which I think is more valuable) is: always take a look at the source code if you are not sure about what a built-in indicator does.
Coming back to the built-in ROC indicator, it uses the following formula:
(Input[0] - Input[barsAgo]) / Input[barsAgo]) * 100
This returns the ROC in percentage, not in points. It is not that difficult to create a new indicator that calculates the ROC in points using the following formula:
Input[0] - Input[barsAgo]
However, there is an easier way. You can “force” the built-in indicator to return the ROC in points by replacing
ROC(myInput, myPeriod)[0]
with
ROC(myInput, myPeriod)[0] * myInput[myPeriod] / 100.
). I didn’t find it out until I looked at the source code in the NinjaScript Editor after much frustration. Therefore, my bonus tip (which I think is more valuable) is: always take a look at the source code if you are not sure about what a built-in indicator does. Coming back to the built-in ROC indicator, it uses the following formula:
(Input[0] - Input[barsAgo]) / Input[barsAgo]) * 100
This returns the ROC in percentage, not in points. It is not that difficult to create a new indicator that calculates the ROC in points using the following formula:
Input[0] - Input[barsAgo]
However, there is an easier way. You can “force” the built-in indicator to return the ROC in points by replacing
ROC(myInput, myPeriod)[0]
with
ROC(myInput, myPeriod)[0] * myInput[myPeriod] / 100.
