How do I create EMA of indicator's iForce output?

Hi,

I want to take an Exponential moving Average of an Indicators iForce output....

double val=iForce(NULL, 0, 35,MODE_LWMA,PRICE_WEIGHTED,0);

so I tried:
double val2 = iMA(val,0,3,0,MODE_EMA,PRICE_WEIGHTED,0);


But the above is incorrect.

What do I have to do in order to take iForce Exp Moving Average

Thanks in anticipation

yeah that was really wrong. the first parameter is a symbol name, or NULL if you want it to be the chart the indicator/EA/script is currently running on (basically the same as just using Symbol() instead of NULL).

if you want to calculate the exp MA of something other than chart prices then you need to calculate them yourself.

let's say you have written yourself an indicator that plots a line showing the iforce number for each bar on the chart. what you then need to do is calculate an ema from THOSE numbers. obviously you'll need to add some extern variables to allow yourself to manually enter what period you want to use etc.

summary : you want, and need, to do to the iforce values what the inbuilt EMA functions do to chart price values.

Put the iForce calculations into an array and then do iMAonArray() to find the MA. Its explained in the documentation.

Its actually not well explained in the documentation at all;

double iMAOnArray(double array[], int total, int period, int ma_shift, int ma_method, int shift)
Calculation of the Moving Average on data stored in a numeric array. Unlike iMA(...), the iMAOnArray function does not take data by symbol name, timeframe, the applied price. The price data must be previously prepared. The indicator is calculated from left to right. To access to the array elements as to a series array (i.e., from right to left), one has to use the ArraySetAsSeries function.

This is not that much help. Have you a sample that you could cut and paste to better demonstrate ?

The documentation explains it better than I can.

I did something like this a couple of years ago (or maybe I fixed it), but I can't locate the code. If I find on the weekend, I will post.

Edit: The main MT4 site usually has code samples. Have you searched for any there?

mql makes things easy for people who use it by making it such that Time[0] or Open[0] etc is the most recent data, and Close[Bars-1] or Volume[Bars-1] is the oldest data.

this is actually bullshit index values. when a new bar forms mt4 doesn't increase the array sizes and then shuffle all data by one space and then set index 0 data as the most recent data. instead, mql simply increases the sizes of the arrays and then sticks the new data at the end of the array at the newly created space. it's exponentially more efficient to not constantly re-shuffle ever-growing arrays and put new data at the start of the arrays, and instead just whack new data at the end of the array and leave everything else alone without shuffling a thing.

so, mt4 automagically calculates the REAL array index when you refer to High[0] or High[24] and so on. you are NOT referencing the data at the real index 0 or 24. you are actually accessing data at index Bars -1 - 0, or the index at Bars - 1 - 24 etc. Bars being a nice little variable that simply stores the current array size of the chart data arrays.

this makes things nice and easy for everyone when all they care about is the most recent data. they can just count from zero upwards to go from the current bar backwards in time. if mql/mt4 did not do things this way then everyones indicators etc would be full of code like : if (High[Bars-1] > High[Bars-21]) .... instead of just if (High[0] > High[20]). it's just easier for people to think in values relative to now, instead of values relative to now which are then relative to the array size.

now, what happens when you create an indicator and declare some indicator buffers that are to be used for outputting some lines or histograms etc? these buffers are treated exactly the same as the chart data arrays.... mt4 is nice enough to automatically resize the buffer arrays for you each new bar, and when you reference some index in the buffer arrays it is in the same reverse format like when you reference the chart data arrays. index N on your indicator will match with index N on the chart.

this is what ArraySetAsSeries is all about. it is a setting that defines whether index 0 is actually index 0, or if it is actually arraysize-1. it defines where to reference indexes from, either the beginning of the array forwards or from the end of the array backwards.

so, what happens when you declare just a normal array and not a buffer? well, mql/mt4 lets you do whatever you want with it. it's up to you to resize it and fill it with data and destroy it once finished. it also means that index 0 is the leftmost index. it is just a normal array, plane-jane everyday simple old array. zero is zero and proceeds left to right like normal just like in every other coding language. when you increase the array size the newly created memory is at the end of the array from the previous arraysize to the new arraysize-1. if you had an array with just 1 element and resized the array to 2 elements then the new spot is at index 1. if you increased by one again then the new array element is at index 2. if you increased it by 100 then the new memory locations are at index 3 to 103.

if you declare yourself an array (not a buffer) but also want to be able to easily reference the data in the array in such a way as it matches with the chart data arrays then you can call ArraySetAsSeries(true) and the way you index the array will now be reversed just like the chart arrays and indicator buffer arrays. (i believe you still have to handle resizing the array yourself, though). zero is actually the end of the array and proceeds backwards right to left.

so this should give you an idea of what iMAOnArray is talking about when it talks about maybe needing to call ArraySetAsSeries. it depends on how you have populated your array with data. if you have called ArraySetAsSeries and are filling your array with data that matches 1 for 1 with the indexes in the chart arrays then when you call iMAOnArray my (possibly completely wrong) understanding is that the iMAOnArray function will reference the data in the same direction as you have been, and so with ArraySetAsSeries(true) it will reference from the end of the array backwards going right to left behind the scenes just like how the chart indexes are. the key here being that how you conceptualize the layout of your data matches a) with how the chart data is arranged, and b) with how you then expect the iMAOnArray function to reference the data..... how it is handled internally is of no consequence and irrelevant because the data you pass is referenced by you and the function in the same way, so you get out of it what you expect to receive without having to do any mental gymnastics to figure out exactly what index matches what and which index should you be requesting from the iMAOnArray function and so on. it all matches 1 for 1.

obviously you don't HAVE to do it like that, it all depends on how you are referencing the data in your array. if you are continually increasing your array size and filling it with new data to match the new bars that form on the chart then it will do you well to use ArraySetAsSeries so that you can reference all indexes the same. if you did not do this and wanted to match index 0 of your array/s with the chart data then each new bar you would have to shuffle all of the data in your array one space to the right and then finally fill index 0 with the data that matches with the chart data at their index 0. this is a slow, painful, wasteful process, and instead it's infinitely better and easier to just flip the switch on the arraysetasseries boolean value for your array and YOU just refer to it as though index 0 is the most newly created position while mql/mt4 internally handles it and actually redirects this index reference to the end of the array instead, or whatever index you happen to be reading or writing to.

as for the values iMAOnArray actually takes when you call it....

you have the name of the array of data that you are passing to it. in your case it will be an array filled with the results from iForce calls.

a 'total' value which is a bit obscure and should just be left as zero to signal using the whole array (yeah i don't quite get what this value is for)

a self-explanatory 'period' value to signal how many bars to average out

an 'ma_shift' value which i believe is just an offset value from the soon to be mentioned 'shift' value.

an 'ma_method' value which just specifies what type of MA you are after... EMA, SMA etc.

and finally a 'shift' value to actually specify which index to return a value for (e.g. bar 0, or bar 10 etc). if you specify zero then the return value will be calculated for the data in your array from index 0 through to 'period' - 1, and then offset by the 'ma_shift' amount (or so i believe).

keeping in mind that this could all be bullshit and wrong.

Thank you Numcake for this most comprehensive reply

I have learnt that you need to setup a loop in order to populate the Array[]

double maValues[];

for(int i=21; i>=0; i--) {

maValues[i] = iForce(NULL, 0, 35,MODE_LWMA,PRICE_WEIGHTED,0);
}

so with the array[] populated I should be able to interrogate for the last value

double val2 = iMAOnArray(maValues,0,3,0,MODE_EMA,1);

BUT THIS DOES NOT WORK - why ???

"does not work" is not, and never will be, an answer that anyone can help you with....

what does it do and not do? what should it do and isn't? what error messages are you getting in your journal or experts tab or wherever it is that mt4 spits out it's complaints (i forget)?

in your little code example i notice you don't mention any arrayresize calls.... i don't know if you are just showing pseudocode or if that's actually what you have exactly written.

need input. more input!

i don't know it is right or wrong, i'm not a coder..

Use Print() to print out the calculate array[] values and related parameters in the journal tab to verify the data is correct or use Comment() to print them on the chart window.

This is exactly what I wanted as an indicator form.

I can now create an array i.e. ExtBuffer[] within the indicator to store the current reading and then interrogate for the current value within my EA via a iCustom ( ) function

Thank you very much Temon and yes you are a coder .

It is proves that you actions in doing something is much more important than just talking about it

By the way I wanted the EMA of iforce index because the iforce index is reset to zero at each new bar change, so using its EMA provides some continuity of value's

thank you.. master..

LOL. LOL. LOL

Brilliant !!!

a multitude of people on this forum who are not amateur coders could have created the exact indicator you wanted, working perfectly, in an hour or less if you had simply asked for what you wanted and had been precise about the requirements. that's not what you asked for. you asked some simple questions, and so you got answers to those questions.

if you don't want to work something out yourself by asking various questions then just get to the point and ask for what you really want. you could have saved yourself a few days time wasted on here going back and forth for nothing, and our time bothering to answer what you did in fact ask about.

the statement i quoted is a pretty big "fuck you" to codemeister and myself who were bored enough to waste our time on you when we could have been doing other things to amuse ourselves. ungrateful.