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4-Participant

## Symbolic partial derivative operator in Mathcad Prime 3 - where is it?

Assuming I have a simple function such that f(x,y)=x^2+x*y+y is it possible with Mathcad Prime 3 to find the symbolic partial derivative of the function f'x(x,y)? For some reason I cannot find how to do this. f' seems to only give a normal first derivative. Is there some tricky keystroke to enable partial derivative notation in MC Prime 3? I find it hard to believe that PTC would have overlooked that functionality?

Kind regards, Mark

1 ACCEPTED SOLUTION

Accepted Solutions
24-Ruby IV
(To:MarkBuckton)

You have to use the detailed derivative operator. While the pic below is from Mathcad 15 (didn't want to wait until Prime3 has started as it takes so long) but its the same in Prime, too. Only difference is that in Prime you can't make it look like a true partial derivative (last line in the pic).

12 REPLIES 12
24-Ruby IV
(To:MarkBuckton)

You have to use the detailed derivative operator. While the pic below is from Mathcad 15 (didn't want to wait until Prime3 has started as it takes so long) but its the same in Prime, too. Only difference is that in Prime you can't make it look like a true partial derivative (last line in the pic).

4-Participant
(To:Werner_E)

I see, but this is not how the text books show partial derivatives of a function. It usually looks like f'x(x,y) or as it is shown in Mathcad 15. I think the current MC Prime notation is incorrect and in my view, shows a degree of laziness on the part of the PTC programmers and could cause confusion.

24-Ruby IV
(To:MarkBuckton)

Mathcad 15 still misses (and ever will be missing) quite some features which where demanded for long times by its users and Prime essentially is missing a lot of features we already are used from Mathcad 15 and below while adding only very few additional benefit (like mixed units in arrays).

Maybe we would need along with the literal and the vector index a third subscript denoting partial derivative to make the confusion as of which subscript to use complete and maybe Prime will offer a better notation for partial derivatives one day.

If you solve a PDE using a solve block with PDESolve, the literal index has to be used to denote partial derivatives anyway and so it follows the usual subscript notation.

For other (documentation) purposes you may define it yourself and hide the definitions in a collapsed area. You can't hide that area completely making it invisible as in MC15 but sufficent enough so its out of the way. So at least you can duplicate the subscript notation from the textbooks.

4-Participant
(To:Werner_E)

Werner;

Thank you for this example. I think you would agree however that all this should not be necessary if partial derivatives were more fully developed. As yet I have not used the partial differential equation solvers as yet but these too look also not to be as easy to use as in Mathcad 15. I also note that there are no good examples in the help file on how to use the new methods.

Kind regards, Mark

24-Ruby IV
(To:MarkBuckton)
 Thank you for this example. I think you would agree however that all this should not be necessary if partial derivatives were more fully developed.

Sure, but its all a matter of what one wants to achieve at the end and if we can achieve it with a simple workaround its better than so many things in Prime without a suitable workaround. Here its just a notation matter but I see so much more severe problems and misses in Prime.

And I never made a secret of my distase for Prime. I still see no reason why anyone working with Mathcad 15 (or 14, or ...) should go and switch to Prime. The few advantages like mixed units in matrices won't justify this in most cases.

 As yet I have not used the partial differential equation solvers as yet but these too look also not to be as easy to use as in Mathcad 15.

I think its the same in both programs. At least apart from the new concept concerning the solve block in general (regardless if used with Find, OdeSolve, PDESolve or others), which I consider less convenient, more cumbersome and very ugly looking.

 I also note that there are no good examples in the help file on how to use the new methods.

I also feel that the help in Prime is much less helpful than the helpsystem in Mathcad, but what do you mean by "new methods"? Neither PdeSolve nor numol are new features, even though PTC would like to make us believe that. See my comment here: http://communities.ptc.com/docs/DOC-5311#comment-13317

4-Participant
(To:Werner_E)

Werner;

I may be incorrect in my assertion but I don't believe PDESolve is available in Mathcad Prime 3. If my hunch is correct, this is yet another example of less functionality in MC Prime. I must say that I agree with what you and others have said when comparing Mathcad 15 with MC Prime. MC 15 is definitely a much faster program to load and use. However, the primary reason I use Mathcad Prime 3 is that it handles units much more adroitly. Inevitably one most go with the flow, although it has been said that "dead fish" also go with the flow.

Kind regards, Mark

24-Ruby IV
(To:MarkBuckton)

PDESolve sure is available in Prime 3. The link I provided at the end of my last post shows that. Its the conversion of a file which used to be part of the Mathcad 11 (!!) distribution. They deleted the mention of making an animation as Prime is not able to do that, but as I ponted out they forgot to delete the mention of the E-book (which is another feature missing in Prime).

4-Participant
(To:Werner_E)

Werner;

I don't see Pdesolve on that sheet only numolPDE solver. Take a look at the sheet attached which has both methods and note that the Pdesolve within the solve block fails to be recognised by MC Prime 3 upon conversion. Have I overlooked something because neither can I find reference to Pdesolve in the function command list,

Regards, Mark

24-Ruby IV
(To:MarkBuckton)

My god, you are right!! I didn't looked further in the file they posted after I realized that is was another sloppily converted old file as so many others. They don't have content and obviously try to feign content that way, requesting some underpaid and clueless employees to convert old files.

I simply assumed from the title of that post and the text that the file would contain a pdesolve() example, but obviously that function is not even implemented in Prime 3!

The files were part of the Mathcad 11 distribution - if you are interested, here are the originals.

4-Participant
(To:Werner_E)

Unfortunately, I detect that PTC is another corporation run by accountants with a certain arrogance about them. If they want to see how a company run by accountants ends up then I suggest they look at the likes of Microsoft under Steve Ballmer or Blackberry under its founders who were both business school dropouts. Unless upper management primary goal is products of technical excellence that empower their users they are doomed. The CEOs must have a deep understanding of how to use Mathcad, it's current limitations, who uses it and listen to customers feedback. What seems to be happing is almost a bait and switch tactic I.e. PTC keeps promising that each new version of Prime will surpass Mathcad 15. I.e. They promise a lot but deliver very little. Mathcad is mature software and it is ridiculous that a 4 year old program is PTCs Standard of excellence. What other software program do people pay for were the upgrade delivers much less than the 4 year old version. PTC have a hide to take money from its users but deliver to them largely irrelevant enhancements such as the ribbon interface. Imagine if PTC marketing department told the truth. "buy Mathcad Prime today and you get a slower program, a clunky interface, no content, a hopeless help system, graphs that don't have grid lines or axis labels, math regions that are hard to align accurately, solve blocks that look like kindergarten toys, no PDE solving ability, bugs in the unit calculations, no way to export the content reliably to a page layout program, no way to number equations and many more negative enhancements".

all this can be yours for just \$460 a year maintenance.

23-Emerald II
(To:MarkBuckton)

PDE solver is planned for the subsequent version after Mathcad Prime 4.0 version.

24-Ruby I