HP 50g fails simple SOLVE. Comparing to TI-89, which succeeds
in [HP48]
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From: Matteo on 11 Feb 2007 17:03 JBGM ha scritto: > Hello everyone. I have a very simple problem in which the HP 50g fails > miserably, and the TI-89 solves only by half. I cannot get the > solution to a simple equation in the HP50g: > SOLVE('LN(X)+SIN(X)+X^2=0', 'X') I receive the error: "SOLVE Error: > Not reducible to a rational expression" I have changed the > configuration parameters in MODE > CAS without success. > > Is there any configuration setting or parameter I am missing? Should I > use another function? SOLVE works fine with a trivial equation; when I > enter SOLVE(' X^2-4*X+8=0', 'X'), it returns {X=2-2*I, X=2+2*i}, which > is correct. > > The TI-89 finds half the answer to the initial problem using the > complex solver command "cSolve(LN(X)+SIN(X)-X^2=0, X)" The TI-89 > returns 0.490672, which is the real root. TI's real solver "solve" > finds the real root too. But the TI-89 fails to return the complex > root 0.8775 + 0.2558i > > The tests were done with PC emulators for HP 50g and TI-89. Could > someone help, please? I would expect the HP 50g to actually find the > complex root, or at the very least the real root, since there is > consensus in the scientific community that HP 50g is superior to the > TI-89 for advanced math. Or is the TI-89 superior? I am trying to > decide which one is better for advanced math in order to purchase it. > > Before someone answers that I should use Maple or Mathematica (how do > you think I obtained the complex root?), here goes the explanation: > I'm a professional mathematician who wants to use a CAS in a handheld > device for a research project. I have to do massive symbolic > computations while I move across large library's shelves, so carrying > a laptop is simply annoying. Hp49g+ (50G) can solve this equation numerically. it is obviusly that it can. :-) you must use the command 'root' in this way: in user rpl mode 3: 'ln(x)+sin(x)+x^2=0' the equation 2: 'x' the indipendent variable 1: 2. the initial value of the variable ---> root and you have the solution. if you want complex solutions you must put a complex initial value for x. With this command (root) you find only one solution.... About calculator cas : I haven't a TI89, but I think that both ti89 and hp49(50) are the most powerful calc with cas in the world. I like a lot the hp cas because every day I discover new features like particular systems flags for solve exact and simbolic big linear sistems 70*70 :) :) :), ecc....and hp has a so powerful programming language that the only thing that you can do i to have dreams...
From: Veli-Pekka Nousiainen on 11 Feb 2007 17:19 "Veli-Pekka Nousiainen" <DROP_vpn(a)dlc.fi> wrote in message news:UiMzh.10681$yD4.9411(a)reader1.news.saunalahti.fi... I tried with checking that REALASSUME list had X and Y defined and that the last flag in the Flag Browser said the Complex Vars are allowed Then I tried: 3: ['LN(Z)+SIN(Z)+Z^2'] 2: ['Z'] 1: [(-1.,-1)] MSLV and I got (using FIX 2 setting to ease up the writing here) 1: [(-1.39,-0.98)] What do you say to that folks?
From: gei209711 on 11 Feb 2007 17:31 On Feb 11, 3:33 pm, "JBGM" <Literatron...(a)gmail.com> wrote: > Hello everyone. I have a very simple problem in which the HP 50g fails > miserably, and the TI-89 solves only by half. I cannot get the > solution to a simple equation in the HP50g: > SOLVE('LN(X)+SIN(X)+X^2=0', 'X') I receive the error: "SOLVE Error: > Not reducible to a rational expression" I have changed the > configuration parameters in MODE > CAS without success. > > Is there any configuration setting or parameter I am missing? Should I > use another function? SOLVE works fine with a trivial equation; when I > enter SOLVE(' X^2-4*X+8=0', 'X'), it returns {X=2-2*I, X=2+2*i}, which > is correct. > > The TI-89 finds half the answer to the initial problem using the > complex solver command "cSolve(LN(X)+SIN(X)-X^2=0, X)" The TI-89 > returns 0.490672, which is the real root. TI's real solver "solve" > finds the real root too. But the TI-89 fails to return the complex > root 0.8775 + 0.2558i > > The tests were done with PC emulators for HP 50g and TI-89. Could > someone help, please? I would expect the HP 50g to actually find the > complex root, or at the very least the real root, since there is > consensus in the scientific community that HP 50g is superior to the > TI-89 for advanced math. Or is the TI-89 superior? I am trying to > decide which one is better for advanced math in order to purchase it. > > Before someone answers that I should use Maple or Mathematica (how do > you think I obtained the complex root?), here goes the explanation: > I'm a professional mathematician who wants to use a CAS in a handheld > device for a research project. I have to do massive symbolic > computations while I move across large library's shelves, so carrying > a laptop is simply annoying. Or you can use the solve equation screen. Use NUM.SLV (right shift 7), menu 1, enter into equation 'ln(x)+sin(x)+x^2=0', move cursor to x and hit solve.
From: JBGM on 11 Feb 2007 17:40 Thank you all for you answers. I confirmed that in deed HP 50g is a better option than TI-89 for my needs.
From: Matteo on 11 Feb 2007 17:48
Yes. I'm wrong about complex solutions with "root". This command can find only real solutions. pardon :-) Without external libraries like the powerful solvesys, the Veli Pekka's method is perfect. and also in this case the solution to the problem is around a flag. fine, very fine! |