Ed, I think your Email was right on point and should not annoy anyone. It is most helpful to point out inconsistencies of a common nature.
I also have missused the "E" notation in exactly the way you discussed without ever giving it a thought. Now I will be constantly checking myself. Bill....WB6BNQ "Ed, k1ggi" wrote: > Chris - > > To help avoid too much confusion, it needs to be pointed out that this 'E' > notation gets used somewhat imprecisely in context, and you have to read > "what they meant" rather than "what they wrote". > > In the convention of scientific E notation, Eb (sometimes eb) denotes a > factor whose value is 10 raised to the power b. > > see > http://en.wikipedia.org/wiki/Scientific_notation > > (This has nothing to do with that mathematical 'e' that gets raised to all > sorts of powers in electronics, etc. -- eb does not mean 2.718... raised to > the power b.) > > Examples: > 3E2 = 3E+2 = 300, a number with two factors, the first being three and the > second being 10 to the power of positive two, or 100. > 8E2 = 800 > 9E2 = 900 > 10E2 = 1000 > 1E2 = 100 > 10E1 = 100 > Calculators such as Excel or Google deal with this notation. > No explicit symbol for a multiplication operator appears within the notation > itself, it is understood. > > Compare this to caret notation, where > a^b denotes a raised to the power b. > 3^2 = 9 > 10^2 = 100 > 3*10^2 = 300 > And just for illustration, > e^-1 = 0.36... where this _is_ the 'other' e thing, 2.718.... > Calculators also understand this notation. > > Now, the values of 10^2 and 10E2 differ by a factor of 10. > 3*10^2 = 300 > 3*10E2 = 3000 > 3*1E3 = 3000 > 3E3 = 3000 > > So here's the thing. When you read about 1 part in 10^2 or 1 part in 10E2, > you find that the writers quite often really meant the same thing, > regardless of the numbers being different, and you have to make a mental > adjustment. > > On this list, where precision and accuracy are so highly regarded, this bit > of ambiguity is accommodated, but if you're not paying attention, a > calculation can be off by a factor of 10. Used equipment also gets described > this way when somebody has to type it up, so it pays to check original > manufacturer's specs. > > With some savvy, it's a good bet that when you see a leading 10, i.e. > 10Eanything, the writer meant to convey only the general notion of the > exponent, not the actual numeric value of the expression. This is because if > the actual value were intended, it would have been written as, say, 1E3 > rather than 10E2. OTOH, any leading number other than 10, as in 9E2, doesn't > readily lend itself to misinterpretation. 10E2 literally means 1000, but may > need to be read as 100, whereas 9E2 always means 900. You would think that > if something goes from 9 to 10 it would come out bigger, but it doesn't. > See? > > <snip> > >an oscillator that is accurate to 1%, is accurate to one part in 100, or > >expressed in scientific notation, 1 part per 10E2. > <snip> > > 10E2 is a number. If you put 1 over 10E2 into a calculator, it doesn't come > out 1%, it comes out 0.1%, 10 times smaller, but here the context reveals > the intent, so there you go. Intent is harder to figure out when there are a > dozen zeros floating around and there is less explanatory context. > > So just be on guard when you see 10Eanything, check for reasonableness, and > consider embracing 1Eanything, which is unambiguous. > > Not intending to drive anyone nuts, > Ed, k1ggi > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
