maColLen = maColLen * (maCol = maCol[1]) + 1 is working differently PRT 11/10

• 01/29/2021 at 11:08 AM #159781
  Daniele Maddaluno

  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…

  maColLen update

  // 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

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

  // 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:

  BarColor

  barCol = +1 * (close > open) -1 * (close < open) + barCol * (close = open)

  1	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.

  

  Daniele Maddaluno

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  01/29/2021 at 11:17 AM #159785
  robertogozzi

  Try initialising it:

  ONCE maColLen = 0 //or any other value

  1	ONCE maColLen = 0 //or any other value

   

  

  robertogozzi

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  01/29/2021 at 11:27 AM #159788
  Daniele Maddaluno

  Yeah, I tried that too (just above the maColLen = maColLen * (maCol = maCol[1]) + 1), but it’s always undefined.

  

  Daniele Maddaluno

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  01/29/2021 at 12:27 PM #159810
  robertogozzi

  Add:

  if BarIndex > maLen then

  1	if BarIndex > maLen then

  at line 4, then ENDIF at line 19.

   

  

  robertogozzi

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  01/29/2021 at 1:47 PM #159834
  Daniele Maddaluno

  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

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

  // 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

  1 2	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

  1 2	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

  1 2	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.

  

  Daniele Maddaluno

  Participant

  Topics: 8

  Replies: 67

  Been thanked: 14 times
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