Ben O'Steen wrote: > On Mon, October 31, 2005 10:23, Sybren Stuvel said: >> Ben O'Steen enlightened us with: >>> Using decimal as opposed to float sorts out this error as floats are >>> not built to handle the size of number used here. >> They can handle the size just fine. What they can't handle is 1/1000th >> precision when using numbers in the order of 1e10. >> > > I used the word 'size' here incorrectly, I intended to mean 'length' > rather than numerical value. Sorry for the confusion :) >
Sybren is right. The problem is not the length or the size, it's the fact that 0.039 cannot be represented exactly in binary, in just the same way that 1/3 cannot be represented exactly in decimal. They both give recurring numbers. If you truncate those recurring numbers to a finite number of digits, you lose precision. And this shows up when you convert the inaccurate number from binary into decimal representation where an exact representation IS possible. Steve -- http://mail.python.org/mailman/listinfo/python-list
