[Tutor] the binary math "wall"
lowelltackett at yahoo.com
Tue Apr 20 18:58:06 CEST 2010
I'm running headlong into the dilemma of binary math representation, with game-ending consequences, e.g.:
Obviously, any attempts to manipulate this value, under the misguided assumption that it is truly "0.15" are ill-advised, with inevitable bad results.
the particular problem I'm attempting to corral is thus:
with some intermediate scrunching, the above snippet morphs to:
The last line should be zero, and needs to be for me to continue this algorithm.
Any of Python's help-aids that I apply to sort things out, such as formatting (%), or modules like "decimal" do nothing more than "powder up" the display for visual consumption (turning it into a string). The underlying float value remains "corrupted", and any attempt to continue with the math adapts and re-incorporates the corruption.
What I'm shooting for, by the way, is an algorithm that converts a deg/min/sec formatted number to decimal degrees. It [mostly] worked, until I stumbled upon the peculiar cases of 15 minutes and/or 45 minutes, which exposed the flaw.
What to do? I dunno. I'm throwing up my hands, and appealing to the "Council".
(As an [unconnected] aside, I have submitted this query as best I know how, using plain text and the "Tutor at ..." address. There is something that either I, or my yahoo.com mailer *or both* doesn't quite "get" about these mailings. But, I simply do my best, following advice I've been offered via this forum. Hope this --mostly-- works.)
>From the virtual desk of Lowell Tackett
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