Defining variable as an equation?

[emürer]

Hello all

I am sorry to say that this problem is not about a exciting, complex and never seen before math problem. It is more of a simple interface problem. I have included a document that describes the issue, but the essence of it is that i want to be able to define a variable as an equation. More specifics in the document.

Many thanks

/Mürer

[Fred_Kohlhepp]

Can't open 3.1.

Post a picture, or save as XPS and attach

[emürer]

Here you go

[Fred_Kohlhepp]

I think I see what you're trying to do.  See if the attached file helps.

(It's Prime 3.0, 3.1 should open and run it.)

[RichardJ]

The way you are writing it makes little sense. If you take all the "equals" to just mean "equal to" (whereas one is actually a numeric assignment, and the other is a boolean equals) you would have x=5=x+3, which is clearly impossible. This is very close to what you want:

[emürer]

Fred Kohlhepp
I must admit that I am a pure MathCad rookie in regards to any of the even only slightly more advanced features. My abilities are limited to Solve, Float and Clear. Even though I can to some extend see what you are doing, I very much doubt that my old-school non-Mathcad trained teacher are going to feel that your solution is more straight forward than just using the "solve" method i described in my file

Richard Jackson

You are certainly correct in respect to x=5=x+3 makes no sense. But I mean it more like x is defined as 5=x+3. With your method I do not get the benefit of actually defining x. Also I essentially introduce another variable called "Equation", which my teacher might not understand the point of. Also i would have to clear() that variable after each calculation.

General

Understand that my teacher is used to getting handwritten(although calculated with a calculator) solutions to equations in the like of just:

5 = x +3
x = 2

Which is why he is complaining about the "messy state" of my MathCad documents. I appreciate very much your ideas but it is unfortunately not really what I am looking for.

/Mürer

[RichardJ]

Unfortunately, what you want is not possible. If you write

5=x+3

Mathcad cannot know what you want to do with that. On a piece of paper you could write something like "given the equation above, solve for x", but Mathcad also cannot interpret arbitrary text strings to figure out what you want. In any computer algebra system you have to give very specific instructions, in a very specific syntax. Until such time that CAS software can interpret arbitrary text strings (or read minds ), you will be stuck with that.

The closest you could get is with Mathcad 15:

But if what your teacher really wants is

5=x+3

Therefore

x=2

you will have to solve in Mathcad, and write your reports by hand.

[Fred_Kohlhepp]

[RichardJ]

Could put the calculations in an area, and collapse it:

[emürer]

Richard Jackson
Yes I see your point and agree fully. Mathcad and any other CAS program needs exact instructions to understand what to do. Problem is that my teacher is not happy with the "telling the program what to do" part of the equation(solve, float etc). Your suggestion about solving in Mathcad, but writting on paper is a solution of course but that would defeat the purpose(in my case at least) of using Mathcad. The 2 main reason for me to use Mathcad is firstly to not having to write down equations twice(ones on the calculator and once one the paper) and secondly to use Mathcad ability to remember results(definitions) which is very handy during a series of many equations. At the exams the time limit is really the difficult part. Being able to shave off a minute here and there is a huge advantage.

Fred Kohlhepp

Ah I see how it works now. Thank you. I will show it to my teacher, but I have a feeling that he wont accept it. From the perspective of an "pen and paper" teacher he most likely will not like MathCad language.

Anyway thanks again guys

/Mürer

[Fred_Kohlhepp]

In Mathcad 15, by judicious use of "hide keywords" and "view evaluation as" I can get this

Prime (at least 3.0) doesn't have that much formatting flexibility.

[RichardJ]

I think what I would do is hide stuff in a collapsed area. It would not completely eliminate manual typing, but it would get rid of a lot of it, and variable definitions would remain for subsequent calculations. Here's what the example I showed above looks like with the area open:

So the equation 5=x+3 has to be copied and pasted once, but that's not much work. Your teacher gets to see just the nice, clean version, you get to put whatever you like in the area. You could even add some text "This is the stuff that confuses my dumb teacher, so I'm hiding it"

If you switch to using Mathcad 15 you can even completely hide the area once it's collapsed.

[LucMeekes]

You say: "At the exams the time limit is really the difficult part. Being able to shave off a minute here and there is a huge advantage."

Does your teacher/school allow you to use Mathcad during exams?

Luc

[emürer]

Fred Kohlhepp
I did actually use Mathcad 15 some years ago back at what would in the states probably be equivalent to college. But I must admit that the interface were quite cumbersome, but much worse were that it were so unstable. Countless hours of schoolwork was lost over the years due to random crashes of the program. Also I feel that it would sort be a step backwards to go back to MathCad 15 when Prime has been out for quite some years now?

Richard Jackson

That is actually a quite neat solution you are proposing there. That would solve my problems without impeding the workflow too much. Only thing is that you can actually see the collapsed area line when printing out. I found an another PTC forum thread that solved that problem:Solved: Hide the "collapsed region" lines when printing a ... - PTC Community

But that must have been in an another version of MathCad or MathCad Prime because I cannot right click on the lines nor can i find any "properties" menu anyway else. Still That could be the solution. I must consult my teacher.

/Mürer

[RichardJ]

Mathcad 15 is far more powerful than Mathcad Prime. Most of us still work in Mathcad 15, because Prime lacks so many features. One such feature is that you can't hide the line. You can in Mathcad 15. The current release of Mathcad 15 is pretty stable. It does crash sometimes, but not often. Just save your work regularly, and make a backup by copying to another folder, because very occasionally a crash will corrupt the file. However, we have seen Mathcad Prime files that were completely trashed posted to the forums, so I would not say that Prime is any safer in that regard.

You can download the latest version here: Thank You for Your Interest in PTC Mathcad 15 | PTC. Point the license wizard at your Prime license file.

[Werner_E]

I agree that Mathcad 15 is far superior compared to Prime, even though the latter is the newer version. Prime is really awkward to handle and much more cumbersome so it takes much longer to have the job done. Furthermore Prime is significantly slower than Mathcad and is still missing a lot of features and functionality.

But if you really for some reason insist to continue using Prime, you may consider putting the calculation to the right, off the right border. Expressions there are fully working but don't show up when you print your worksheet. I guess you have to turn in a printed sheet and not the file itself.

[RichardJ]

Yes. Sort of an area without a line

MC15 is the better way to go though (a point on which we have never had an argument ).

[emürer]

LucMeekes
Yes we are allowed to use whatever calculator or program we wish. Only communication to the outside world(i.e the internet, phones etc) are not allowed. Usually an exam is between 2 and 8 hours. Every minute counts.

Werner Exinger
That is actually also a decent solution and would also solve the problem with very long equations that results in the equation being wider than the printable page. Starting from this semester and onwards, we actually have to turn our work digitally in the form of a PDF, so having the calculations outside the printable area is just fine as the file are going to be "printed" as a PDF anyway.