Seriously pesky bug!! :(

ZTrader · #1 (**permalink**) 12-30-2008, 04:10 PM

I've been programming a long time and this is one of the most confusing bugs I've come across. It almost seems like a flaw in MT4 but I know from experience that it's most likely a mistake on my part. Try as I will, though, I can't for the life of me figure out what's wrong.

The offending indicator code is attached - BEWARE THAT IT WILL CRASH MT4!!

I've isolated the problem to line 107:

Code:

      for (g = 0; g < dSmoothDomPeriod[k] / 2; g ++)
         {I3 += Q3[g];}

It seems that MT4 gakks when I try to use the expression 'dSmoothDomPeriod[k] / 2' as a limit for the for() statement.

I tried putting the value into a separate variable of int type:

Code:

      int temp = dSmoothDomPeriod[k] / 2;
      for (g = 0; g < temp; g ++)
         {I3 += Q3[g];}

But it didn't help.

I tried using the MathFloor() function to explicitly truncate the expression:

Code:

      int temp = MathFloor(dSmoothDomPeriod[k] / 2);
      for (g = 0; g < temp; g ++)
         {I3 += Q3[g];}

Again, no dice.

I tried explicitly casting the value into an int type (rather clumsy):

Code:

      int temp = StrToInt(DoubleToStr(MathFloor(dSmoothDomPeriod[k] / 2), 0));
      for (g = 0; g < temp; g ++)
         {I3 += Q3[g];}

Strike three.

If I replace the expression with a constant or with a variable loaded by a constant, everything is fine:

Code:

      for (g = 0; g < 50; g ++)
         {I3 += Q3[g];}
-->this works fine...

      int temp = 50;
      for (g = 0; g < temp; g ++)
         {I3 += Q3[g];}
-->this also works fine...

But of course that's not what I need...

I even tried changing to a while() statement, using all the same variations as above:

Code:

      int g = 0;
      while (g < dSmoothDomPeriod[k] / 2)
         {I3 += Q3[g];
         g ++;}

Still no go.

Please take a look at the code and see if you can figure out what I need to get it to iterate using the results of the required expression without locking up the host application. This code is for a Hilbert Signal To Noise Ratio indicator, and if I can get it to work, it should be pretty cool... Seems like a very big if right now...

Z--

Michel · #2 (**permalink**) 12-30-2008, 08:10 PM

several small bugs; the main one concerns indeed the line:

PHP Code:


			
      for (g = 0; g < dSmoothDomPeriod[k] / 2; g ++)

         I3 += Q3[g];

which should be (I think):

PHP Code:


			
for (g = 0; g < dSmoothDomPeriod[k] / 2 && k+g < Bars; g ++) I3 += Q3[k+g];

Attached is the fixed version.

Perky · #3 (**permalink**) 12-30-2008, 09:27 PM

maybe you have a divide by zero in there crashing it all

Roger09 · #4 (**permalink**) 12-31-2008, 12:33 AM

You have:

Code:

double dSmoothDomPeriod[];

should be

Code:

int dSmoothDomPeriod[];

or

Code:

double dSmoothDomPeriod[];
....
int x=dSmoothDomPeriod[k]/2;

ralph.ronnquist · #5 (**permalink**) 12-31-2008, 02:21 AM

Perhaps the bug would go away if you added "SetIndexEmptyValue(1,0);" to the init() method.
My guess is that without this, dSmoothDomPeriod[k] may be a quite large number for some k. Then the Q array becomes too large for the computer memory and bad things happen.

Roger09 · #6 (**permalink**) 12-31-2008, 03:46 AM

I tryed to realized your logic and couldn't. Lots of uncertainty as a:
I1[k] = dDeTrend[k + 3].
if k=Bars-6, you don't know dDeTrend[k + 3] because you didn't calculate it yet.

Kenny Rogers · #7 (**permalink**) 12-31-2008, 05:38 AM

I'm putting my money on Michel, he's a good coder.

ZTrader · #8 (**permalink**) 12-31-2008, 05:45 AM

Yes, Michel gets the nod. I had already noticed that I needed to use Q3[k + g] and not just Q3[g], but I hadn't realized that the algorithm was invalid at some values of k + g. Michel's fix did the trick, and now the whole world can easily determine the signal to noise ratio of their favorite charts...

Thanks, Michel!!

waltini · #9 (**permalink**) 01-01-2009, 09:18 AM

A quick coding question whilst everyone is around if that is ok.

I want my ea to take a trade every time the price is at a round number for example 1.4000 and when that trade is complete wait for the price to reach another round number to initiate another trade.

So its not a grid which is easy but I need the ea to recognise the price ends in 00.

I have tried using a few different things, I am even dividing the price by 100 and counting the length of the answer using stringlen() but the string function keeps adding zeros to the price.

Many thanks

Michel · #10 (**permalink**) 01-01-2009, 11:31 AM

PHP Code:


			
bool IsRoundPrice = MathMod(Bid/Point,100) < 1;