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Well Pierre, we all know you will never admit a bug in an Omega product and
that will have to be ok, but could you not stop confusing others with your
theories? Funny enough, your latest reasoning is more the definition of what
a bug is, something that should not happen but does happen, than a proof
against it. Not even most theoretical schools would accept a proof like "The
DMI bug does not exist since Pierre says it can not exist since Pierre says
the marketing material says it should be calculated as long precision". Get
back to the real world Pierre, look at what happens in reality, not what
Omega tells you should happen.
The DMI bug is easy to verify, it is an easy calculation to do, and it is
also easy to provide the data for displaying the bug. And it is so easy that
seeing the bug can be done with the built in write protected buggy version
of PlusDM included in Tradestation. Without using any testprintouts at all.
So here comes a way of seeing the bug without test printouts. Try it for
yourselves, create a new indicator, which does "plot1(dmiplus(5));", that is
all that is needed.
Then use the indicator on the below data, which can either be written to an
ascii file, or which is made available to you as a number of metastock data
files by Mark Brown. Then look at the plot value of 990416, you can see that
it is higher than for the day before. This is since the PlusDM calculation
decided that the low difference (minusDM) of 0.05 is not higher or equal to
the high difference (plusDM) of 0.05, due to the precision error. Thus the
DMI is given a higher value than yesterday though adding a number to the old
value, when instead it should be given a lower value by just removing part
of the old value. The difference can amount to around 30% on this single
bar. This is not the only example in the data base, the difference in DMI
timing is plus minus 5 bars or more due to this bug which Pierre still
claims does not exist (he would never sink so low as to look at real data
when there is marketing material available from Omega). You do not even need
a calculator to verify that this should not occur, just look at the data
values and compare to the rules in the buggy DMI implementation.
04/01/1999 7.0000 6.7000 6.7000 26100
04/06/1999 6.9500 6.5000 6.6500 23700
04/07/1999 6.8500 6.5000 6.6000 20300
04/08/1999 6.7500 6.6000 6.6000 25320
04/09/1999 6.8500 6.6500 6.7000 15500
04/12/1999 6.7500 6.6000 6.7500 31800
04/13/1999 6.8500 6.6000 6.6000 20250
04/14/1999 6.7500 6.6000 6.6000 21700
04/15/1999 6.7500 6.6000 6.6000 34000
04/16/1999 6.8000 6.5500 6.7500 36800
04/19/1999 6.7500 6.5000 6.5000 17836
04/20/1999 6.6000 6.4000 6.5000 78600
04/21/1999 6.6000 6.5000 6.5000 21700
04/22/1999 6.7500 6.5000 6.5000 30800
04/23/1999 6.7000 6.5000 6.5000 12050
04/26/1999 6.5000 6.5000 6.5000 34000
04/27/1999 6.5500 6.3000 6.4000 63500
04/28/1999 6.6000 6.2000 6.6000 72200
04/29/1999 6.6000 6.4000 6.5500 52250
If you do not want the hassle of saving ascii data to a file and reading it
through tradestation, you can download the above data and a number of bars
more from mark brown. Create a new empty directory somewhere on your
computer, go to http://www.markbrown.com/free/ in your browser, download the
files "f1.dat" and "master.dat". Rename master.dat to master. Then open that
directory in Tradestation as a metastock directory, and the same data as
above is on your screen. Now use your indicator, and look att 990416.
My original testprogram earlier sent to this list finds any similar
occurences in your own data base, but this is not the important thing,
important is that you need to change the calculations, using for example
Bobs solution, so this does not happen to you during trading or backtesting.
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