Given Find Solve Block Error

[DavidHill]

Hi,

Attached is a sample section of a larger mathcad sheet where I'm trying to solve a simple simultaneous equation.

An error is produced and I am unsure of where my error is?

I was wondering if anyone could help me out, as I'm relatively new to MathCAD

Thanks

David

[MikeArmstrong]

Where are R.A and R.B defined in your worksheet?

Have a look at the attached, I have started to clean your worksheet up.

Mike

[DavidHill]

Sorry, I thought I had managed to get all the definitions in, clearly missed out Ra and Rb

I've attached the updated document,

Would it possibly be due to the fact im working in Newtons? or am i just stabbing in the dark,

I have no clue where I'm going wrong with the error

Thanks again!

David

[MikeArmstrong]

That seems to be the same worksheet.

Yes it can be done, but you need to define all know variables.

Mike

[DavidHill]

Sorry about that,

here is the document again with the Ra and Rb values in...

Its more the error message i'm confused by, why is it returning this error?

Thanks again, I appreciate your help

David

[MikeArmstrong]

Have a look at the attached. You have to create a function and call the solve block that way.

Mike

[wayne]

Thanks Mike,

I goophed.

Should also set ORIGIN=1, since `case starts at 1

[DavidHill]

Thats a great help to me! Thanks,

I now however have trouble calling values from that function

(3,85 0.222)

(3.722 0.04)

etc....

how do I get them,

whenever i used P.A or P.B it gives me the guess values?

Any ideas?

[MikeArmstrong]

Sorry about that. I knew they where being returned as a nested matrix, but didn't have the time to sort it.

Mike

[wayne]

Currently, you have two equations, one for RA and one for RB, they are not simultaneous, there is nothing for the solve block to do.

[DavidHill]

Ra and Rb are just values,

there are 4 sets (due to the variable `case) of 2 simultaneous equations (Ra and Rb) to produce values for the two unknowns Pa and Pb built into the mathcad sheet - I think?

David

**see updated mathcad sheet**

[wayne · Accepted solution]

David,
added some to Mike's solution.

[DavidHill]

Sorry for being very unknowledgable but...

I'm trying to get the values for Pa and Pb ?

Thanks for your help!

[wayne]

David,

sorry, just change the R's to P's

[MikeArmstrong]

Wayne,

I think it does need a vectorize operator, see attached I have used a small program to solve it.

Mike

[wayne]

Mi Mike,

The Func(R.A,R.B) = Find(P.A,P.B) did not need to be vectorized, it's no longer vectorized in you file, but it was. No big deal, worked either way, just that the guess values are now not vectors, so to there was no need to vectorize.

[MikeArmstrong]

Oh sorry Wayne, I think I was getting mixed up - still in holiday mode

Look below what happens if the definitions of the find function does not get vectorized.

Mike

[DavidHill]

Thanks very, very much for your help guys,

Apologies about the delay in getting back to you, I really appreciate the help you gave me!

Not only solving my problem but I learnt a great deal along the way!

Thanks again

David