[math-fun] Article on math education
I wonder how those prospective teachers would have fared
comparing 7^sqrt(8) vs. 8^sqrt(7) instead of 1/13 vs. 0.13
I originally misread this as "comparing 7*sqrt(8) vs. 8*sqrt(7)", which is actually a pretty good question for diagnosing underlying math knowledge. (I'm afraid that many of them, if told "You can do this in your head", would object "You can't expect us to compute square roots without a calculator!") Jim Propp
JPropp>I originally misread this as "comparing 7*sqrt(8) vs. 8*sqrt(7)", Analogously, suppose you want 2^(1/12) and have 2^(1/3) and 2^(1/4), but subtract instead of dividing. (E.g., maybe you can only get the beat frequency.) "No problem." If a:=2^(1/3)-2^(1/4), then 1/12 11 10 9 8 7 2 = (- 126360 a + 76707 a - 28614 a + 1050384 a + 45198 a 6 5 4 3 2 - 277596 a - 3218520 a + 26497700 a - 15686172 a + 12188460 a + 18908336 a + 7114424)/8030072 "I ask for a half tone and I get a bleeping cadenza!" (Btw, a~~sqrt(2)/20.) On a related note, in the late 70s I found a suite (>= six) of identities like 5 a 2 1 1 | a, --- + -, a - -, a + - | 3 3 5 5 | 125 F ( | ---) = 4 3 5 a 1 5 a 1 5 a 3 | 128 --- - -, --- + -, --- + - | 3 3 4 4 4 4 | a 7 a 3 a pi (- - --)! (- - --)! 8 csc(--) 2 10 2 10 5 ------------------------------ . a 3 a 2 2 (- - -)! (- - -)! 2 5 2 5 My Merriam-Webster gives 125/128 as a definition of "enharmonic diesis", but refers to it as a difference! (That's OK, I have identities at 3/128 as well.) Are there any other named fractions besides "one half", "one quarter", and "enharmonic diesis"? Maybe "cent" and "percent"? --rwg cart horse - horsecart - orchestra sacher torte - orchestrate panettones - nonseptate - ten past one - pentatones supersonic - percussion higher test - High Street - eighth rest ciguateras - guitar case guitermanites - time signature ostentous - sostenuto necrotic - concerti pangolins - plainsong snoutiest - sostenuti canotier - anoretic - conarite - cortinae - creation - reaction - cantorie actinon - contain - cantion - cantino typhonian - antiphony Dantean - andante poetaster - operettas hyponyms - symphony rhetorics - chorister costumiers - music store normalcies - sermonical - minor scale impairers - primaries - primieras - impresari abrotine - beta iron - obtainer - baritone - taborine monometer - monotreme - metronome separator - sea parrot - opera star paternoites - proteinates - street piano Aaronic - Nicarao - conaria - ocarina underarms - snare drum tragions - roasting - organist assorting - Gastornis - organists partimento - armipotent - portamenti band shell - handbells aerophores - horse opera (and of course the maraschino Chorasmian harmonicas) .ucf.edu andrews@math.psu.edu elh@osots.com jford343@sbcglobal.net rudy@rudyrucker.com BuckonBass@aol.com adr@flex.com wrn@verizon.net ef@cmu.edu
At 07:39 PM 12/20/2004, R. William Gosper wrote:
Are there any other named fractions besides "one half", "one quarter", and "enharmonic diesis"? Maybe "cent" and "percent"? Duh, three quarters?
I find the same "difference/ratio" definition of enharmonic diesis in Webster's Third New International Dictionary. I think they mean to define all of these to be intervals (in the musical sense) rather than fractions, but some similar terms from the same dictionary are ditone "corresponding to the ratio 81:64" ditonic comma "represented by the ratio 531,441:524,288" limma "256/243" syntonic comma "represented by the ratio of 81:80" Feeding these terms into Google turns up a very long list of interval names at http://www.xs4all.nl/~huygensf/doc/intervals.html ; ordered by numerator, it ends with "Mercator's comma", which is 3^53:2^84. -- Fred W. Helenius <fredh@ix.netcom.com>
participants (3)
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Fred W. Helenius -
James Propp -
R. William Gosper