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1-AUG-2019 SolveSys - Equation Library and Nonlinear Systems Solver
05-06-2019, 12:33 AM (This post was last modified: 05-06-2019 12:37 AM by Han.)
Post: #112
RE: 25-MAR-2017 SolveSys - Equation Library and Nonlinear Systems Solver
(05-05-2019 08:10 PM)rrpalma Wrote:  Hello,

I'm trying to solve the following system using SolveSys:
(X/Y)^Z = 1/8

On the HP50g, I just use the equation writer to place all 3 equations on the stack, then create an array with them. I then create an array with [X Y Z] and another with my initial guesses [1 1 1]. I go to NUM.SLV-->MSLV and then get an array with 2, 4 and 3 as the answers.

However, when trying to solve this system on the Prime using SolveSys, I get the following message: Newton iterations terminated but ||F|| failed tolerance
The (incorrect) answers that I get are X=1.505 Y=4.984 Z=2.759

What am I doing wrong?

Probably nothing. The message simply means that the pre-set number of iterations were reached but that the solution was still not obtained. I have not tried the system myself or even looked at the mathematical reasons, but just an initial gut feeling based on your numerical values I would say the system is slow to converge numerically. Just re-run the solver again and see if the values get closer to the solution found on the HP50G.

EDIT: What I mean is to run the solver using the current values for X Y and Z as your new initial guess. You can also change the max number of iterations in the options. Lastly, you should be able to see the result of each step to at least see if the convergence is slow.

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Messages In This Thread
Not able to solve a system - rrpalma - 05-05-2019, 08:10 PM
RE: 25-MAR-2017 SolveSys - Equation Library and Nonlinear Systems Solver - Han - 05-06-2019 12:33 AM

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