About an example concerning PDE written in the help of MATHCAD 15 : unexplainable error.

Funny that the error message tells you the opposite from whats the cause:

Actually  you don't miss a "Given" - on contrary - if you disable the closing "Pdesolve" line of a solve block, you would also have to disable the corresponding opening "Given". Otherwise you end up with a giant solve block with probably conflicting equations, constraints and conditions and a second "Given" in the middle, which Mathcad chokes on.

This can't happen with the ugly solve blocks in Prime but of course they have other limitations.

BTW - you don't use any symbolical evaluations, so the expressions u:=u, etc. will have no effect at all! There is no way to clear variables (other than for the symbolics) in Mathcad 15 and below.

Hi F.M.,

seems you discovered another "nice feature", or is this really wanted ? I don't know.

While I was playing with your file I found out that this is not

only restricted to "pdesolve", but also to "odesolve" and" Find",

maybe to other equation solvers as well (haven't tried yet).

You can overcome this, if you copy the second solve block and paste it

just below, so that you would have actually three solve blocks :

The disabled one, and the other two that are enabled.  The third block will work then.

Of course,this is not an acceptable workaround.

If you would  also disable the second solve block the third will generate an error message, too,

so that you would have to copy the second solve block below the third.

This would lead to four blocks a. s. o.

This seems to be independent on either you try to solve for different equations,

or if you try to solve for the same equation.

As already said before, I have no idea, if this is wanted or not,

Regards

hfeith