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Re: End of this phase

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Thu, 15 Sep 2011 22:42:32 +0200

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 ```On Thu, 15 Sep 2011 13:51:43 -0400, Ray Denenberg, Library of Congress wrote > > y193.9e1 is 1939 with decade precision, the 9 in 1939 is "estimated" > > Still need more clarification. Are you saying > > (a) "193.9e1" is commonly understood to mean the 9 in 1939 is "estimated" > > (b) "y193.9e1" is proposed to mean that. Normally scientific notation is used for BIG or small numbers.. In a number such as 123.4e20 the 4 is comonly considered an "estimated digit".. see http://en.wikipedia.org/wiki/Scientific_notation "Significant figures   Ambiguity of the last digit in scientific notation   It is customary in scientific measurements to record all the significant digits from the measurements, and to guess one additional digit if there is any information at all available to the observer to make a guess. The resulting number is considered more valuable than it would be without that extra digit, and it is considered a significant digit because it contains some information leading to greater precision in measurements and in aggregations of measurements (adding them or multiplying them together).   Additional information about precision can be conveyed through additional notations. In some cases, it may be useful to know how exact the final significant digit is. For instance, the accepted value of the unit of elementary charge can properly be expressed as 1.602176487(40)×10−19 C,[7] which is shorthand for 1.602176487±0.000000040×10−19 C." > > (c) or both. > > If (a), I don't see what there is in that expression that denotes > estimation. I would read 193.9e1 to mean 1939 (exactly). If you wanted to say exactly you would be better off saying 1939.. > > > Why the estimate? There are loads of reasons.. > > I don't question the usefulness of this, I question the syntax. If you are The notation I suggest is inspired by this but without the ambiguity and instead of "last digit" I have proposed here ALL the digits right of the decimal point build the estimate.. that is right of decimal points is an estimate.. and left is "exactly" but, of course, to the precision defined by the exponent.. > saying (a) above, then it's news to me, that's not how I learned it, but I > will defer to your expertise, and in that case I am fine with this change. > If on the other hand that's not what you mean, than I am not comfortable > with the proposed syntax. > > --Ray See also http://www.chem.tamu.edu/class/fyp/mathrev/mr-sigfg.html (just found this page but seems a good intro..) -- Edward C. Zimmermann, NONMONOTONIC LAB ```