cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

explicit evaluation

SOLVED
Highlighted
Newbie

explicit evaluation

hello

i just introduced to the explicit evaluation (just 2 days ago) and having some problems..

see attached

1) can i set a limit to the number of decimal places in explicit evaluations?

i tried limiting it in the "format > result", "tools > worksheet options" ..

i want to limit the decimal places of x2 (in the explicit evaluation of h2), i don't need that many decimal places displayed.

2) can the explicit evaluation use the latest value?

something like this

h2=80.431Btu/lbm

in

wt:=h1-h2 explicit h1,h2 -> 91.278Btu/lbm - 80.431Btu/lbm

NOT

wt:=h1-h2 explicit h1,h2 -> 91.278Btu/lbm - [ 0.9314...(84.56 ... )+ 24.511 Btu/lbm]

1 ACCEPTED SOLUTION

Accepted Solutions
Highlighted

Re: explicit evaluation

gLanzer,

Use the float keyword on the Symbolic toolbar.

re-define h2 and h2=h2 float,2 prior to using in the equation, OK, or where h2 is originally calculated.

View solution in original post

16 REPLIES 16
Highlighted

Re: explicit evaluation

gLanzer,

Use the float keyword on the Symbolic toolbar.

re-define h2 and h2=h2 float,2 prior to using in the equation, OK, or where h2 is originally calculated.

View solution in original post

Highlighted

Re: explicit evaluation

There's no need to use 'explicit' in your third example. It's not doing anything.

Clipboard01.jpg

Mike

Highlighted

Re: explicit evaluation

I do not use explicit. It is impossibly with units.

I do so:

NotExplicit.PNG

Highlighted

Re: explicit evaluation

Like below?

Clipboard012.jpg

Mike

Highlighted

Re: explicit evaluation

Thanks Mike

Should review before I post, The real answer was to use float on the variables before using in the equations with explicite, or expand in your case.

(By extrapolation, I am not doing anything right now either, should I delete myself?)

Highlighted

Re: explicit evaluation

(By extrapolation, I am not doing anything right now either, should I delete myself?)

You displayed the use of integrals right the other day.

Mike

Highlighted

Re: explicit evaluation

The real answer was to use float on the variables before using in the equations with explicite, or expand in your case.

That is not a good approach. The float keyword does not affect just the display precision, it affects the precision used for the calculation. An expression like x:=x,float,2--> is the same as rounding x to two decimal places. The only reason I can think of to ever use the float keyword is if you are actually trying to determine the effects of calculation precision on the final result.

You can get the results formatting to apply to the intermediate symbolic result. Due to a bug you have to do it in a very specific way though.

Highlighted

Re: explicit evaluation

Another thing I have missed.

Clipboard01.jpg

Mike

Highlighted

Re: explicit evaluation

It's a new option. It exists only in MC14 and MC15.

We do get at least some of the things we ask for, at least some of the time

Highlighted

Re: explicit - fatal problem

The main and fatal problem of the Explicit operator is that this operatot is one SYMBOLIC tool.

But symbolic tool of Mathcad cannot work with units, number formating tools, DLL-functions etc.

PTC must honestly say it to Mathcad-users!

But each serios Mathcad-sheeet must have units, DLL-functions etc

Two Example.

A Little task - a little problem

simple-explicit.png

A big task (with DLL) - a big/fatal problem:

not-simple-explicit.png

Highlighted

Re: explicit - fatal problem

Valery,

Is this a bug?

Clipboard01.gif

Mike

Highlighted

Re: explicit - fatal problem

No. The symbolic processor does not understand units. It just sees mm and in as undefined variables. It's no different to writing 1*sakjas+1*sakldjka. It drops the numerical value because it's 1 and displays sakjas+sakldjka.

Highlighted

Re: explicit - fatal problem

No. The symbolic processor does not understand units. It just sees mm and in as undefined variables. It's no different to writing 1*sakjas+1*sakldjka. It drops the numerical value because it's 1 and displays sakjas+sakldjka.

Oh yes, of course. Another case of

Mike

Highlighted

Re: explicit - fatal problem

Mike Armstrong wrote:

Valery,

Is this a bug?

Clipboard01.gif

Mike

It is not a bug. But I would like to see 1 mm + 1 in and more than I can create using Mathcad explicit operator.

I do not use explicit and do so:

MyExplicit.png

I can show by this technology of "explicit" not only variables values with different units, but values of parts of formulas etc.

Full this calculation see here http://twt.mpei.ac.ru/MCS/Worksheets/PTU/PGU-eng.xmcd

or see the picture below:

PGU-eng.PNG

Highlighted

Re: explicit - fatal problem

It is not a bug. But I would like to see 1 mm + 1 in and more than I can create using Mathcad explicit operator.

I do not use explicit and do so:


Cheers Valery. I second this request.

Mike

Highlighted

Re: explicit evaluation

thank all.

very helpful indeed.

Announcements