Solving a non-linear, non-polynomial system of equations -- SOLVED
05-05-2019, 07:38 PM (This post was last modified: 05-05-2019 08:33 PM by rrpalma.)
Post: #1
 rrpalma Junior Member Posts: 25 Joined: Aug 2014
Solving a non-linear, non-polynomial system of equations -- SOLVED
Hello,

I'm in the process of familiarizing myself with my new Prime. I'm very familiar with the HP42/DM42 and especially with the HP50G.

I think the Prime is an extremely powerful calculator, and am enjoying the learning curve. It amazes me how fast it is, and if I go back to the 50G, I find myself continuously tapping at its screen :-)

However, I'm still confused about how to do certain things on the Prime, one of them being solving multiple non-linear equations.

Let's suppose I have the following system:
(X/Y)^Z = 1/8
2^X/3^Y=4/Z^4
X*Y/Z=8/3

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.

On the Prime, I go into CAS mode, then I define:
EQ1:=((x/y)^z) = 1/8
EQ2:=(2^x/3^y) = 4/z^4
EQ3:=(x*y/z) = 8/3

Then I type:
L0:=solve({EQ1,EQ2,EQ3},{x,y,z})

And I get the following error:
{"[x,2^x] is not rational w.r.t. x Error: Bad Argument Value"}

What am I doing wrong?

EDIT
===
OK, I found what I was doing wrong!! I forgot to provide the guesses. My mistake; my apologies for asking dumb questions.
Got it to work with:
L0:=solve({EQ1,EQ2,EQ3},{x,y,z},{1,1,1})

05-05-2019, 11:10 PM
Post: #2
 rprosperi Senior Member Posts: 4,325 Joined: Dec 2013
RE: Solving a non-linear, non-polynomial system of equations -- SOLVED
(05-05-2019 07:38 PM)rrpalma Wrote:  Moderators: please delete this post....

Nah... leave it here; you're answer will help someone in the future looking for info about the same problem. So thanks for posting the answer you found for yourself; most folks simply don't come back to update the question with the answer.

--Bob Prosperi
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