I have run into what I consider to be a very irritating bug and wonder if
others see it as a bug also.
If I have a channel with DUMMY values in it and I execute an expression
similar to the following
if( Chan < 10 ) Chan = 0.0
the DUMMY values are changed to 0.0 as well. In my view DUMMY values are
invalid data and should NEVER be included in any data manipulations wheter
it be calculations or filters. In most cases, any calculation should
either not use values that are DUMMY and should ensure that the channel
value remains set to DUMMY. In many other cases, the result channel should
also be set to DUMMY because the result of the calculation is invalid if
any channel in the calculaiton is invalid.
Another problem I noted is that the non-linear filter will also modify
dummy values under some conditions. I am not sure exactly what the
criteria are but it does seem to modify DUMMY values near the end of a
line. This is also a clear bug that violates the rule that DUMMY values
should never change.
Does anyone view DUMMY values in a significantly different manner than I
have outlined above?
The consequences of these bugs is to cause hidden effects that can be very
difficult to fix if the process that identified the DUMMY values is complex
and follows a non-reversible logic.
*******************************************************************************
Joseph (Joe) S. Duval
Geophysicist, Eastern Mineral Resources Team
12201 Sunrise Valley Dr. MS 954
Reston, VA 20192
Phone: 703-648-6106 FAX: 703-648-6383
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