I was just writing this simple code, and I noticed that it’s working differently in PRT v10 and v11 (“LMAX v10.3 – 1.8._202” and “IG v11.1 – 1.8._202”).
On v11 I am getting the expected behaviour, on v10 it’s odd…
// Settings
once maLen = 20
once maType = 1
// Indicators
ma = Average[maLen, maType](close)
// Color of ma line
if(ma > ma[1]) then
maCol = +1
elsif(ma < ma[1]) then
maCol = -1
else
maCol = maCol[1]
endif
// this variable should give me the distance from the last changement of color
maColLen = maColLen * (maCol = maCol[1]) + 1
return maColLen, maCol
The problem is with the “maColLen”, on v10 is always undefined, on v11 it works as I expected…
At first I thought that it was “(maCol = maCol[1])” considered as a boolean and not as a 0/1 as it normally should and could not work as it should.
But I tried this other small piece of code and I understood that it’s not the case, because this is working good on both v10 and v11:
barCol = +1 * (close > open) -1 * (close < open) + barCol * (close = open)
So I think that the problem is linked to the “maCol[1]” inside of the “(maCol = maCol[1])”.
Or maybe it’s me that I have misunderstood something…
I would like to have a clearer understanding of this at a low level.
Thank you in advance.
Try initialising it:
ONCE maColLen = 0 //or any other value
Yeah, I tried that too (just above the maColLen = maColLen * (maCol = maCol[1]) + 1), but it’s always undefined.
Add:
if BarIndex > maLen then
at line 4, then ENDIF at line 19.
Thank you for the correction proposal to make it works.
Ok it works now… And I can understand the correction.
// Settings
once maLen = 20
once maType = 1
if barindex > maLen then
// Indicators
ma = Average[maLen, maType](close)
// Color of ma line
if(ma > ma[1]) then
maCol = +1
elsif(ma < ma[1]) then
maCol = -1
else
maCol = 0
endif
// this variable should give me the distance from the last changement of color
maColLen = maColLen * (maCol = maCol[1]) + 1
endif
return maColLen, maCol
But I still don’t completely get why they reacted differently.
So I have done some research on that and now I think i’m getting closer at why at low level it’s working differently.
Fact 1:
PRT 10 and 11 behaves completely differently when it comes to compare a value with the undefined.
myvar = undefined
return myvar = 4
This is returning undefined on PRT v10 and zero on PRT v11…
Fact 2:
A simple variable as maColLen by default (if not used with a function like average on the right of assignement) is 0, and you can prove that with that indicator (which returns 0 both on PRT 10 and 11):
myVar = myVar
return myVar
Fact 3:
A simple variable as maCol if it’s set equals to maCol[1] on first bars will give you undefined (both on 10 an 11):
myVar = myVar[1]
return myVar
So now that I have those fact in mind we have three cases:
- bars < 20
- ma is undefined
- maCol is undefined (for fact 3, for the else line of ma color)
- so maColLen = maColLen * (maCol = maCol[1]) + 1 —> maColLen = 0 * (undefined) + 1 on PRT 10 and maColLen = 0 * (0) + 1 on PRT 11
- bars = 20
- ma is a value but ma[1] is not a value
- maCol is undefined (for fact 3, for the else line of ma color)
- so maColLen = maColLen * (maCol = maCol[1]) + 1 —> maColLen = 0 * (undefined) + 1 on PRT 10 and maColLen = 0 * (0) + 1 on PRT 11
- bars > 20
- ma and ma[1] is a value
- maCol is a value +1, -1 (i’ll not consider the ema to be flat between bar 20 and 21)
- so maColLen = maColLen * (maCol = maCol[1]) + 1 —> maColLen = 0 * (a value) + 1 —> why at this point PRT 10 should not work? I don’t get this…
Is this all correct? Or I’m wrong at a certain step?
I’m not getting why PRT 10 is not giving values… i.e. why on the bulleted list above “bars > 20”, point third is still not working on v10.
I just wish I had a better understanding of what’s going on.
Thanks again for your patience.
