jn190068@longs.LANCE.ColoState.EDU (Jay Lewis Nestle) (09/26/90)
Thanks to all of the 48SX gurus out there!!!
I do see the light now. The notation seemed to just
throw me off, sorry for rehashing an old topic.
Thanks again :-))))) Happy 48SX user, Jay.
jn190068@longs.lance.colostate.edu
...ncar!boulder!ccncsu!longs.lance.colostate.edu!jn190068
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| |johnt@uccba.uc.edu (John Townsend) (09/26/90)
In article <9700@ccncsu.ColoState.EDU>, jn190068@longs.LANCE.ColoState.EDU (Jay Lewis Nestle) writes: |> |> Thanks to all of the 48SX gurus out there!!! |> I do see the light now. The notation seemed to just |> throw me off, sorry for rehashing an old topic. This reminds me of when I first got my HP-28C when I was in college. The first thing I did with it was "acid-test" it by calculating the cube root of -27. Every sixth-grader knows that the answer to this is simply -3, but most calculators (including every TI I've ever seen) gag on it. Up to that time, the only calculator I'd seen give me a correct answer was a Sharp EL506-P that I'd gotten for about $10. Well, my $200 28C coughed out "(1.5,2.59807621135)". "Bug!!!", I screamed. Fortunately, before I could send any hate mail to HP, a friend of mine who was taking Complex Variables at the time reminded me that I was actually solving a cubic equation, which always has THREE correct answers in the complex number domain. Turns out that the 28C returns the first of these (going around the complex plane counterclockwise from the X axis). The other two solutions are (-3,0) and (1.5,-2.59807621135). The 28C will cube all of these back into -27. That sure raised by opinion of HP in a hurry! -- John Townsend Internet: mead!johnt@uccba.uc.edu c/o Mead Data Central UUCP: ...!uccba!mead!johnt P.O. Box 933 Telephone: (513) 865-7250 Dayton, Ohio, 45401
ryoder@ecn.purdue.edu (Robert W Yoder) (09/27/90)
In article <1473@meaddata.meaddata.com>, mead!johnt@uccba.uc.edu (John Townsend) writes: > > In article <9700@ccncsu.ColoState.EDU>, > > This reminds me of when I first got my HP-28C when I was in college. The first > thing I did with it was "acid-test" it by calculating the cube root of -27. > Every sixth-grader knows that the answer to this is simply -3, but most > calculators (including every TI I've ever seen) gag on it. Up to that time, > the only calculator I'd seen give me a correct answer was a Sharp EL506-P that > I'd gotten for about $10. Well, my $200 28C coughed out "(1.5,2.59807621135)". > "Bug!!!", I screamed. Fortunately, before I could send any hate mail to HP, > a friend of mine who was taking Complex Variables at the time reminded me that > I was actually solving a cubic equation, which always has THREE correct answers > in the complex number domain. Turns out that the 28C returns the first of > these (going around the complex plane counterclockwise from the X axis). The > other two solutions are (-3,0) and (1.5,-2.59807621135). The 28C will cube all > of these back into -27. That sure raised by opinion of HP in a hurry! This feature caused me enormous headaches when trying to debug a root solver sometime back. It never occured to me that a calculator might return a complex cube root. On the same topic, here is a program I wrote that finds ALL of the roots of any real or complex number and puts them on the stack in order, as they are arranged around the origin. To solve X^(1/N) = Y for Y: Input: level 2: X Input: level 1: N Output: roots in stack levels 1 to N RTCX << -> z0 n << z0 ABS n INV ^ z0 ARG n / (0,1) * EXP * (0,2) n / [pi] * EXP -> m a << 0 n 1 - FOR k a k ^ m * ->NUM ROUN ;ROUN is optional NEXT >> >> >> -- Robert Yoder 306 Hawkins Graduate House, West Lafayette, IN 47906 (317)495-6845 Internet: ryoder@ecn.purdue.edu "Flame all you want, We'll post more." UUCP: pur-ee!ryoder Apologies to Jay Leno & Doritos. Bitnet: ryoder@ecn.purdue.edu@purccvm.bitnet
rrd@hpfinote.HP.COM (Ray Depew x2419) (09/29/90)
Recognizing that the temperature mathematics as incorporated in the HP48SX UNITS application still left something to be desired, HP included a couple of fixes in the HP Equation Library card. In the UTILS menu you will find two functions, labeled TDELTA and TINC. TDELTA returns the difference (delta-T) between two temperatures. The units of the Level 2 argument are preserved in the result. Examples: 20_oC 20_oC ----> 0_oC 120_oC 90_oF ---> 87.78_oC 70_oF 30_K ---> 475.67_oF TINC adds the temperature increment (Tinc) in Level 1 to the temperature in Level 1. The units of the Level 2 argument are preserved in the result. Examples: 20_oC 20_oC ---> 40_oC 70_oF 10_oC ---> 88_oF 273_K 90_oC ---> 383_K Think of TDELT and TINC as "the other subtraction and addition functions." Regards Ray Depew HP Colorado IC Division rrd@hpfitst1.hp.com
lishka@uwslh.slh.wisc.edu (a.k.a. Chri) (09/29/90)
mead!johnt@uccba.uc.edu (John Townsend) writes: >This reminds me of when I first got my HP-28C when I was in college. The first >thing I did with it was "acid-test" it by calculating the cube root of -27. >[...] Well, my $200 28C coughed out "(1.5,2.59807621135)". >"Bug!!!", I screamed. >[...] _ Hmmm...interesting. When I type "-27 3 x\/Y" (where the last bit is "take the x root of y") my HP48sx returns -3, which is the answer one would expect (although there are two other complex answers, as was pointed out by the above posting). -- Christopher Lishka 608-262-4485 "Dad, don't give in to mob mentality!" Wisconsin State Lab. of Hygiene -- Bart Simpson lishka@uwslh.slh.wisc.edu "I'm not, Son. I'm jumping on the bandwagon." uunet!uwvax!uwslh!lishka -- Homer Simpson