Minimise value in solve block

[JB_10745469]

Hi,

I am looking to find a minimum value of 'ey' within a solve block based on a set of equations, which otherwise give a circular reference.

So far I cannot manage for the solve block to give me an answer and I was looking for some help.

Screenshot of problem:

Using PTC Mathcad Prime 8.0.0.0

Thanks,

JB

[terryhendicott]

Hi,

Only have version 9.

Take all the functions outside the solve block

Define a function for ey the function to minimise.

Set ey as the thing to minimise

[LucMeekes · Accepted solution]

In Prime 7 I get an error message, that it can't find a solution.

A little more tweaking:

gives:

Success!
Luc

[JB_10745469]

Thanks for the solution @LucMeekes and thanks to the other replies.

I did make it a little confusing when I set the solver to solve for 'XYZ' - this was just a random term to solve for a minimum value of 'ey' but did not fully realise I had 'X', 'Y' and 'Z' already within the equations!

Also, as 'X' was a fixed value, I managed to remove it from within the brackets of the beta equations.

[Werner_E]

It looks like you will have to supply additional information!

Which quantity should be as small as possible? Is it e.y as Terry had supposed or is it beta.ey as Luc had?

Also necessary: Which of the variables you defined may be varied to achieve this goal? Terry varied X,Y and Z.end while Luc varied e.y.

Generally you have to know that the quantity you would like to minimize must be a function depending on the quantities you are willing to vary to achieve this goal. You can't minimize a variable.

[terryhendicott]

[Werner_E]

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@terryhendicott wrote:

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yes, I saw this. But he defined a guess value for e.y which normally means that e.y is the value to vary and even if he saw e.y as function to minimize its absolutely not clear to me which variables should be varied to achieve this goal.

Anyway, a timely feedback from the questioner on the two suggestions already given and further clarification would be quite appropriate and necessary in my opinion.

[LucMeekes]

Given the relation between the two:

It shouldn't matter much which one is minimised, Given that all other symbols in the relation are constants, the minimum of one results in the minimum of the other.

Success!
Luc