topic Re: embarrasing "not defined" in solve blocks in Mathcad

embarrasing "not defined" in solve blocks

Efried — Thu, 03 May 2018 18:37:02 GMT

I'm rather frequently get stuck with Mathcad 14 claiming that a variable is not defined- but its not a variable but a function at the left side of a find statement,The solve block indeed works pretty well with a vector on the left side of the find statement.I have the impression

Re: embarrasing "not defined" in solve blocks

Fred_Kohlhepp — Mon, 24 Oct 2011 20:12:15 GMT

Tracing and troubleshooting errors in Mathcad has long been an art form; like Microsoft's, the error messages only rarely point to the actual problem. (Believe it or not, things have actually improved since early days!)

Soldier on!

Re: embarrasing "not defined" in solve blocks

MikeArmstrong — Mon, 24 Oct 2011 20:39:46 GMT

The solve block indeed works pretty well with a vector on the left side of the find statement.
I have the impression that copying into a new sheet sometimes helps. I think this is an error by

I find copying the equation side of the solve block and checking the units helps. Also, by copy/pasting somewhere outside the solve block you should find the undefined variables.

Mike

Re: embarrasing "not defined" in solve blocks

MikeArmstrong — Mon, 24 Oct 2011 20:40:22 GMT

(Believe it or not, things have actually improved since early days!)

Still not up to scratch though Fred!!!!!

Mike

Re: embarrasing "not defined" in solve blocks

VladimirN — Tue, 25 Oct 2011 07:21:10 GMT

Gerfried Cebrat wrote:
...I have the impression that copying into a new sheet sometimes helps. I think this is an error by design...

Could you give an example (Mathcad worksheet)?

Re: embarrasing "not defined" in solve blocks

Efried — Tue, 25 Oct 2011 13:27:46 GMT

once I thought Umlaute is the problem, then all Variables and Functions have to be included in the solvefunction, but neither helps- attached the proof that it works with the vector asignement...

Re: embarrasing "not defined" in solve blocks

MikeArmstrong — Tue, 25 Oct 2011 13:31:11 GMT

Unfortunately there is not much I can do with a *.pdf. Can you not post the worksheet?

Mike

Re: embarrasing "not defined" in solve blocks

Efried — Thu, 27 Oct 2011 07:10:55 GMT

I was now trying the same thing with ODE solve and think it works. The problem in my previous attempt was an integral which had been evaluated numerically for the standard solve block and failed when using a function to solve for different parameters, at least that is my impression. Mathcad evaluates the parameters diferently.

Re: embarrasing "not defined" in solve blocks

MikeArmstrong — Thu, 27 Oct 2011 10:40:39 GMT

I'm sorry Gerfried, the help your going to receive will be limited if you do not provide a Mathcad worksheet.

Mike

Re: embarrasing "not defined" in solve blocks

Fred_Kohlhepp — Thu, 27 Oct 2011 11:58:06 GMT

It's difficult to tell from your pdf but sollve blocks require one given (Vorgabe) and one Find (Suchen), a second find without a second given doesn't work.

Attached is a mathcad file and two pdf's pf that file, one with a solve block function and one as a single block.

Re: embarrasing "not defined" in solve blocks

Fred_Kohlhepp — Thu, 27 Oct 2011 12:03:23 GMT

A Given/Odesolve (Vorgabe/Gdglosen) block will return a function, your T_R is a function of y for the values of I,alpha, and t that you had in the DGL_T() finction that defined T_R(y). You can now have the solutions of different cases by adding different values:

T_R2 := DGL_T(I2,a2,t2) where T_R2 is actually a function T_R2(y)

T_R3 := DGL_T(I3,a3,t3)

etc.

Re: embarrasing "not defined" in solve blocks

Efried — Fri, 28 Oct 2011 16:17:44 GMT

The solution provided by Andy in another forum was to remove the units in the variables in the find expression of the solve block - for example t.l/K.

thanks to all for your endeavour

Re: embarrasing "not defined" in solve blocks

Efried — Mon, 31 Oct 2011 19:29:42 GMT

I'm sorry, I have to say that the removal of the units in the find statemnet results in wrong solving!

So back to the start! The behavior of Mathcad s so strange that I insist that it is buggy.

Re: embarrasing "not defined" in solve blocks

ksmith-2 — Tue, 22 Sep 2015 15:06:03 GMT

This is an old thread, but a common error I've seen is if you have open solve blocks it will confuse things.

For example:

Define your variables

"Given"

Equation

Find(x) -> 'variable not define'