topic Re: Change to symbolic calculation in Mathcad

Change to symbolic calculation

RantEng — Tue, 10 Jan 2023 13:30:43 GMT

In earlier versions of Mathcad Prime, I could write the following expression:

Simply put, I could define a variable symbolically and display the answer. With the changes to the symbolic engine on Primate, this can no longer be done:

This feature was great because I often used Mathcad during Engineering lectures to work examples problems. My work around is:

The first properly should use the symbolic equal to "=" and not the mathematical definition ":=" but it still works. Anyone have any better suggestions or work arounds?

Bob

Re: Change to symbolic calculation

Werner_E — Tue, 10 Jan 2023 13:49:36 GMT

I can't verify this, as I haven't bothered to install a newer version of Prime yet (I'm still using Prime 6).

But chances are that you ran into Primes infamous auto-labeling bug.

You may try to enable units and constants in symbolic calculations, recalculate and see if it helps

Re: Change to symbolic calculation

RantEng — Tue, 10 Jan 2023 14:53:53 GMT

Thanks Werner!

I completely missed that option because I really didn't understand the PTC explanation of it. I had experimented with the setting in the past but didn't see what change it made.

Bob

Re: Change to symbolic calculation

Werner_E — Tue, 10 Jan 2023 17:30:25 GMT

@RantEng wrote:

Thanks Werner!

I completely missed that option because I really didn't understand the PTC explanation of it. I had experimented with the setting in the past but didn't see what change it made.

Bob

This calculation options is sometimes a cure when experiencing problems with symbolic operations with expressions and quantities containing units. But this forum already showed a lot of examples where enabling this option unfortunately still is no cure to a problem.

The reason the evaluation failed in your case seemed to have been that the unit "mm" was not labeled as being a unit and so was treated as an unknown variable. And maybe development changed the way expressions are handed over to the numeric engine when a symbolic evaluation is directly followed by a numeric evaluation.

Glad to see that in your case turning on this calc option solves the problem.

Re: Change to symbolic calculation

RantEng — Thu, 23 Feb 2023 17:26:16 GMT

Thanks again Werner,

I completely forgot how you solved that problem for me. Had to go back and look at the old messages.

It works great when you remember to recalculate!

Bob