How solve - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: How solve (/thread-8790.html) |
How solve - yingwuluo - 08-08-2017 03:48 AM 1-x*2.72^(-50*y)=100/z 1-x*2.72^(-100*y)=150/z 1-x*2.72^(-150*y)=250/z RE: How solve - ettlz - 08-08-2017 03:05 PM With a pen and paper? \(x=-\frac12\), \(y=-\frac{\log_{2.72}2}{50}\), \(z=50\) RE: How solve - Helge Gabert - 08-08-2017 03:10 PM Starting values? Any ideas what the feasible solution space should look like? Using fsolve(), with blind values x=-.1, y=-.1,z=.1*i, I get [-.5, -1.38 . . .E-2, 50]. RE: How solve - AlexFekken - 08-09-2017 01:52 AM (08-08-2017 03:05 PM)ettlz Wrote: With a pen and paper? \(x=-\frac12\), \(y=-\frac{\log_{2.72}2}{50}\), \(z=50\) Yes! Really sad that somebody would even try a calculator or computer for a problem like this. RE: How solve - yingwuluo - 08-09-2017 03:26 AM solve([1-x*e^(?50*y)=100/z,1-x*e^(?100*y)=200/z,1-x*e^(?150*y)=250/z],[x,y,z]) [/b] ["[y,e^(-50*y),e^(-100*y),e^(-150*y)] is not rational w.r.t. y Erreur: Valeur Argument Incorrecte"] fsolve([(1-x*e^(-50*y)) = (100/z),(1-x*e^(-100*y)) = (200/z),(1-x*e^(-150*y)) = (250/z)],[x,y,z],[-0.1,-0.1,-0.1*i]) undef Above output is the result from HP Prime Graphing Calculator, something wrong with it, please help me check if there is any input mistake. RE: How solve - parisse - 08-09-2017 05:52 AM You can help solve by rewriting the system as a rational system Code: solve([(1-x*t) = (100/z),(1-x*t^2) = (150/z),(1-x*t^3) = (250/z)],[x,t,z]) Code: solve(e^(-50*y)=t,y) Code: fsolve([(1-x*e^(-50*y)) = (100/z),(1-x*e^(-100*y)) = (150/z),(1-x*e^(-150*y)) = (250/z)],[x,y,z],[-0.1,-0.1,0.1]) RE: How solve - yingwuluo - 08-09-2017 09:14 AM i tried to input i in solve symbolic view,it shows that irror:invalid input,please help me fix this problem. RE: How solve - Helge Gabert - 08-09-2017 01:58 PM You didn't use the starting values I mentioned in my above post. [-.1,-.1,.1*i] Works for me. RE: How solve - yingwuluo - 08-09-2017 03:03 PM What are the theory for using this starting value. i tried to input i in solve symbolic view,it shows that irror:invalid input,please help me fix this problem. RE: How solve - Arno K - 08-09-2017 04:00 PM I, as well as the others, I think, have not tried it in the solver-app. Switch to the command-line, I tried it in CAS, and the above mentioned entry beginning with fsolve(...) will do the job. Arno RE: How solve - yingwuluo - 08-09-2017 09:34 PM Thank you all. The members here are very active in solving the problem. |