Ideally there should not be any difference even you take 60days chart data or 100 days chart data as the maximum price/days look back period is 14days for ADX and 10 days for EMA for analysing our Buy/Sell trigger.
Karthik
Both ADX and EMA use a fraction of the previous value to calculate the present value. So, the fraction of previous value contains all the previous values. So, the number of candles included in calculation affects value of ADX and EMA. When the previous data available is sufficiently large, the difference becomes neglible.
The calculation of EMA differs from software to software. For an EMA period of n-days, the EMA can not be calculated by the standard defined formula if the number of candles available is less than or equal to n. So, the EMA for initial n candles is calculated by different methods by different software. Some use Simple MA for first n days and then change over to standard formula. Some others use progressive simple moving average for first n days. This way the calculated EMA for first n days differs from software to software. This EMA for first n candles in turn affects the EMA value of subsequent candles. Therefore, the cross-overs and values of ADX will differ from software to software unless a large number of data points is used. For a calculation of EMA 3 & 10 and ADX 14 using about 60 candles will show a wide variation compared to the values obtained with say 500 or more candles.
I have checked these manually using Excel.
In addition, what is displayed on chart will be restricted to 2 or 3 decimal places with rounding off, but what is used in calculation and comparison will be with more decimal places. So, a difference in 6th decimal may appear as a cross-over on chart but internally it will not be a cross-over. This also can cause difference in the charts posted.
-Anant