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ptc-54606851-Visitor
1-Visitor
January 11, 2014
Solved

Non- linear equations system solution

  • January 11, 2014
  • 25 replies
  • 11342 views

I have a serious problem with my graduating thesys... I have to solve a system of four non linear equation but I'm not able to do it... Could you help me please???

Best answer by AlanStevens

You'd simply forgotten to make we a function of m in the 2nd equation within the solve block - see attached.

Alan

25 replies

Werner_E
Werner_E25-Diamond I
25-Diamond I
January 11, 2014

Two errors spotted:

  • s(t): Either make it a constant or you have to provide a value for t or you solve for t in the Find command
  • Y.3 is not defined

I'm am confused about the parameters (x,y,z,k) of your function F() as none of those parameters is used anywhere. So the result of the solve block would be the same constant every time. In case of the guess values and equations you provided Mathcad does not find a solution anyway (at least not with Y.3 set to 1, as I did). The first equation yields something about 10^19 if evaluated with your guess values - a bit far away from the zero you want it to be. So it may be you have to check your guesses and/or your equations.

The error message you get with a solve block is usually more than misleading and confusing. Use the right click menu and chose trace error to get a hint what the real problem could be.

ptc-54606851-VisitorAuthor
1-Visitor
January 11, 2014

I corrected the error abut Y3 but it doesn't find a solution again... substantially I have to find the stationary solution of a system of differential equations and placing d/dt equal to zero I obtained the non linear equations system I sent you before. Now I send you both 2 files, the diff eq system and the non linear one. Thanks for the help

AlanStevens19-Tanzanite
19-Tanzanite
January 12, 2014

In your dynamic model you should set ORIGIN:=1 as you are clearly counting from 1, biut Mathcad's default is to count from zero.

In your static model, remove t, Y3 should be Ti, divide the equations through by n, and create a function for ni so you only have to solve for 3 parameters (actually, if you know that ni is always going to be twice n then you could simply replace ni by 2n).

See attached.

Alan

ptc-54606851-VisitorAuthor
1-Visitor
January 12, 2014

could you send me the 2 files in an elder mathcad format please? I can't open these in mathcad 13, my version

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