MathCAD is unable to solve simple equations

[BB_14100646]

I'm using MathCAD 9.0.0.0. How come MathCAD is unable to solve these simple equations?

[NickKemaev]

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[Werner_E · Accepted solution]

Two problems:

1) You should turn on the option "Units/Constants in Symbolics" and then recalculate the worksheet (Ctrl+F5)

The symbolics still doesn't not know anything about units now but this option at least avoid that units get labeled wrongly as "Variable". I have no idea why this option is not permanently on per default.

2) If you want to see a value as percent, you can't simply type a "%" in the unit placeholder. This worked in real Mathcad, but in Prime most things are mor cumbersome and time consuming (with the exception of editing matrices and using Ctrl-J in programs).

You must use the menu for results formatting

BTW, you are not solving equations but just evaluating mathematical expressions, terms 😉

[BB_14100646]

Thank you!

[DJNewman]

It can, but you're running into the limitations of expressing things with explicit in the symbolic engine for numerical math problems with units; the symbolic engine doesn't natively understand units.

Here's how I might express it (although this is a screenshot from Prime 11 so me attaching the worksheet wouldn't help you):

Those thick equal signs is a Boolean equal sign (keyboard shortcut: CTRL and =, or under the Comparison group in Operators in the Math tab) but it has a side effect of presenting an equation without actually evaluating it. It's good for documentation purposes.

Or you can do that, I guess.

(I... don't know why the bottom one is so WEIRD.)


Edit: Okay now I can just skip that step on the bottom one but I swear it was giving me an error before.

[SPaulis]

I am getting similar results in Prime 11.0.0.0.0.0.0.0.0...

It seem like you want to show your intermediate step.  I long to have that option because sometimes my variables are defined a few pages previous and it is nice to show the reviewer the numbers that come into a formula. but this method is terrible since the symbolics engine does not work with units very well.  For engineering calculations, this gets way to confusing and unprofessional (i.e. ugly).  Especially when we compare it to handwritten calculations.  And don't get me started on the width constraints in WYSIWYG documents!!!! 

They should have a separate command, not a symbolics command, that only shows the equation with all variables substituted.  AND to have a 'step' feature where you could show the calculation is stages (pausing before the addition/subtraction step—there are good reasons for that).

[Werner_E]

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@SPaulis wrote:

I am getting similar results in Prime 11.0.0.0.0.0.0.0.0...

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Its necessary to let the sheet recalculate after you set the calc option about units in symbolics.

And I sure second your demand for a command which shows the variable values used in a calculation.
We also need a way to make large symbolic results readable within the page width. Instead of cutting off portions of the expression when we resize the region it should rather show the expression in multiple lines. Some built-in intelligence would be needed to decide where a line brak makes sense.

According you "step" feature I am not sure how this should work and how this would fit with the general concept of Mathcad as a whiteboard doodle pad. But PTC has already broken this concept several times, for example, in the implementation of solve blocks or in the completely botched implementation of the chart component (apparently it was much easier to do that way than properly improving the native plots).

[SPaulis]

Yeah, I was only showing that the option was turned on.  I was trying a few combinations and nothing worked, even after calculation.  

I love-hate this program!!!!! 

It's hard to explain but I made an Excel macro that was able to read formulas and do the automatic iterative calculation "steps"... and some modest formatting😏.  This is kinda what I would like Mathcad to do.  If can do this with Excel, and I am a lowly VBA programmer, imagine what the PTC programmers can do with the barrels of our subscription money!!!

[Werner_E]

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@SPaulis wrote:

Yeah, I was only showing that the option was turned on.  I was trying a few combinations and nothing worked, even after calculation.  

That's strange, but you would have to send the non-working worksheet for further investigation. As you can see in the screenshot I posted, the calculations worked OK once the option was checked, the percent number format was chosen and the sheet recalculated.

If can do this with Excel, and I am a lowly VBA programmer, imagine what the PTC programmers can do with the barrels of our subscription money!!!

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When you look at Prime's development 'speed', you don't get the impression that revenue is being channeled into program development. The development department seems to me to be rather understaffed and underfunded.