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Solve block error: "Not a valid constraint"

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Solve block error: "Not a valid constraint"

In the attached image of a mathcad prime 3.1 worksheet I'm attempting to call the function in a solve block and from another function. I receive the error: "This is not a valid constraint, Use, for example, the equal to operator."

 

Am I making a syntax error that I'm not aware of?

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Accepted Solutions

Re: Solve block error: "Not a valid constraint"

I had not noticed that in the meantime you added the worksheet.

 

There are three problems:

 

1) The inline evaluation when you specify the guess for L.b. This is responsible for the irritating error message, Delete the equal sign after 3/4*D

 

2) You specify the guess for f.max to be sigma.maxlift, but sigma.maxlift ist not defined in your worksheet. You have to provide a value!

 

3) You have to define B and a, too, or you make them additional arguments of your function FUCNTION.

 

Here is a screen shot where I had chosen arbitrary values just to show that it works now:

clipboard_image_0.png

View solution in original post

16 REPLIES 16

Re: Solve block error: "Not a valid constraint"

1. Send please the Mathcad-sheet.

2. Try in first line so

A:=find...

and than

A(x):=find...

 

Re: Solve block error: "Not a valid constraint"

Thanks ValeryOchkov. The worksheet is currently 91 pages, I'll try to shorten it and then post it.

 

What do you mean by "Try in first line so..." 

 

Do you mean adding FUNCTION:=Find(,) and then under it FUNCTION(F,Mtoe):=Find(,)?

The solve block seems to only like one :=Find

 

Re: Solve block error: "Not a valid constraint"

Yes! 

Re: Solve block error: "Not a valid constraint"

It doesn't seem to like 2 "Find:=" in the same solve block

Re: Solve block error: "Not a valid constraint"

I've added a mathcad worksheet and the excel it imports to the original post

Re: Solve block error: "Not a valid constraint"

In your MapLb function, you call the function FUNCTION with and index: Can't see it well (you should always attach a worksheet!), I believe it's index 11.

But FUNCTION is the result of the solve block above. It isn't a vector, so you cannot index it.

 

Success!
Luc

Re: Solve block error: "Not a valid constraint"

Thanks LucMeekes. I've attached a worksheet (and referenced excel) and removed the indexes but still no luck

Re: Solve block error: "Not a valid constraint"

have you tried to call the solve block FUNCTION in a separate region with the very same arguments?

have you tried to use the trace option in the calculation menu to see if the error traces back to the solve block?

Re: Solve block error: "Not a valid constraint"

I had not noticed that in the meantime you added the worksheet.

 

There are three problems:

 

1) The inline evaluation when you specify the guess for L.b. This is responsible for the irritating error message, Delete the equal sign after 3/4*D

 

2) You specify the guess for f.max to be sigma.maxlift, but sigma.maxlift ist not defined in your worksheet. You have to provide a value!

 

3) You have to define B and a, too, or you make them additional arguments of your function FUCNTION.

 

Here is a screen shot where I had chosen arbitrary values just to show that it works now:

clipboard_image_0.png

View solution in original post