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PierreTOMASINI1-Visitor
1-Visitor
April 19, 2020
Solved

Solving system of non-linear equations

  • April 19, 2020
  • 2 replies
  • 6272 views

Hello All,

    I am struggling to find the proper code for solving a system of non linear equations, using Mathcad 15.

    The equation are given in the screenshot below. The problem is related to thermodynamics.

 

    I followed a template with Find, however it just don't get me anywhere.

    What needs to be done to get the results ? Can someone explain the issue (for the layman).

 

   Thanks for the support,

 

   keep safe,

 

System of equations

     Result sough PA (Pas in code) and PS (Ps in code).

     Once PA and PS are available; related parameters "aS", "aA" (aA and aS in code) and x calculations are straightforward.

PierreTOMASINI_0-1587254607502.png

 

Code (Mathcad file attached)

 

Untitled2.png

Untitled3.png

 

 

 

 

Best answer by Werner_E

Here is my attempt for a solution.

Basically the problem was wrong syntax for the solve block and that you wrote your function definitions as if they were equations.

But using your values and equations the solve block could not find a solution. Either use much lower guess values or change other values (as written in the file) or maybe have a second look at your functions to see if there is something wrong with them.

Werner_E_1-1587294110438.png

 

 

2 replies

T
terryhendicott21-Topaz II
21-Topaz II
April 19, 2020

Hi,

File enclosed you will need to check the equations and values as it does not solve properly.

 

You only need two equations for two unknowns.  You need a "Given" statement to start the solve block.

 

Cheers

Terry

 

P
PierreTOMASINI1-VisitorAuthor
1-Visitor
April 19, 2020

Many thanks Terry for the quick reply.

Take care

Pierre

W
Werner_E25-Diamond IAnswer
25-Diamond I
April 19, 2020

Here is my attempt for a solution.

Basically the problem was wrong syntax for the solve block and that you wrote your function definitions as if they were equations.

But using your values and equations the solve block could not find a solution. Either use much lower guess values or change other values (as written in the file) or maybe have a second look at your functions to see if there is something wrong with them.

Werner_E_1-1587294110438.png

 

 

P
PierreTOMASINI1-VisitorAuthor
1-Visitor
April 19, 2020

Thank you. That's really great. I was worried by the 0 values from the previous post.

Thank you.

Pierre

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