Simple EMA Question

[ramckay]

I want to display the difference of two EMAs as an indicator. I want the first EMA to be calculated on the highs of bars and the second to be calculated from the lows of bars. I tried:

EMADifference.Set(EMA(High,3)- EMA(Low,3));

NT tells me this doesn't work. Can someone point out the error in my approach?

Thanks

[NinjaTrader_JoshP]

You cannot subtract the EMA indicators from each other like that. You need to subtract actual EMA values.

EMADifference.Set(EMA(High, 3)[0] - EMA(Low, 3)[0]);

[ramckay]

Thanks Josh,

One more question. I want to use the EMA values from one bar back.

EMADifference.Set(EMA(High,3)[0]- EMA(Low,3)[0]);

gives me the value for the EMA differences of the current bar but I would like to see what they are for the previous bar.

EMADifference.Set(EMA(High,3)[1]- EMA(Low,3)[1]);

This line of code compiles but nothing is displayed. Obviously another mistake here somewhere.

[roonius]

Thanks Josh,

One more question. I want to use the EMA values from one bar back.

EMADifference.Set(EMA(High,3)[0]- EMA(Low,3)[0]);

gives me the value for the EMA differences of the current bar but I would like to see what they are for the previous bar.

EMADifference.Set(EMA(High,3)[1]- EMA(Low,3)[1]);

This line of code compiles but nothing is displayed. Obviously another mistake here somewhere.

Include the following line in the begining of OnBarUpdate:

if(CurrentBar == 0) return;

[ramckay]

Hi roonius,

That solved the problem. What's the basic logic for when you need to use a DataSeries to hold values and when you don't?

Thanks,

rod

[roonius]

Hi roonius,

That solved the problem. What's the basic logic for when you need to use a DataSeries to hold values and when you don't?

Thanks,

rod

If you do some calculations on a bar basis and then need to access them later, you store the values in DataSeries. If you don't need to access those values later (after n bars) then you don't need DataSeries.

[e-man]

hey rod - if you wanted to run an EMA against EMADifference, then you would want to set that inside a DataSeries, but if you're just plotting it, you should be OK with your current method.

EDIT: or, in other words: what roonius said

[ramckay]

Thanks guys,

Rod