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ptc-50909611-Visitor
1-Visitor
May 18, 2013
Question

Can someone help me?

  • May 18, 2013
  • 5 replies
  • 3359 views

Hi, I have a system of 11 equations. I need to find what are values of these 11 variables. For example I brought value 1 and I wanted to see if the system works. It doesn't work and I don't understand why...Maybe I don't know how to make a system of equations in mathcad...Can someone look what's the problem?

5 replies

V
VladimirN24-Ruby III
24-Ruby III
May 18, 2013

Hi,

Try to use "Minerr" function instead of "Find".

W
Werner_E25-Diamond I
25-Diamond I
May 18, 2013

VladimirN. wrote:

Hi,

Try to use "Minerr" function instead of "Find".

Would not help. As there are only two different equations Mathcad would set 9 variables to zero and minimize for the remaining two.

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Werner_E25-Diamond I
25-Diamond I
May 18, 2013

You have 11 variables to solve for, but only 2 different equations! You first 9 equations are ident as are the last 2, because you set all coefficients to 1.

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ptc-50909611-VisitorAuthor
1-Visitor
May 18, 2013

But there must be some answers to system. I will change everything from 1 to another numbers later. But now it doesn't show me any answers.

P
ptc-50909611-VisitorAuthor
1-Visitor
May 18, 2013

I need answers like in this picture (it doesn't matter 1 or other number).

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Werner_E25-Diamond I
25-Diamond I
May 19, 2013

Jonas Jonaitis wrote:

I need answers like in this picture (it doesn't matter 1 or other number).

It DOES matter!!!

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ptc-50909611-VisitorAuthor
1-Visitor
May 18, 2013

Here's a full system of equations. Why it doesn't calculate x1, x1 and etc... ?

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Werner_E25-Diamond I
25-Diamond I
May 19, 2013

Provide guess values and Mathcad returns a solution

system11.png

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ptc-50909611-VisitorAuthor
1-Visitor
May 19, 2013

Thanks very much for help I didn't know how to provide guess values..

W
Werner_E25-Diamond I
25-Diamond I
May 19, 2013

Jonas Jonaitis wrote:

Thanks very much for help I didn't know how to provide guess values..

No problem.

BTW, you provided guess values yourself in your very first attachment but you deleted it in the second and third.

Guess values simply are normal assignments to the solve variables at the beginning of a solve block or in front of it. In case of an underdetermined system the guess values may influence which solution Mathcad will arrive to.

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