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ptc-57822981-Visitor
1-Visitor
April 9, 2014
Question

how to save calculated data for later use so that Mathcad does not recalculate every time I open the worksheet

  • April 9, 2014
  • 3 replies
  • 11913 views

Hi all,

I know that a related question has been asked, but it seems complicated for me to impliment. So, I was hoping if there is a easier way out. My problem is as follows:

I have a mathcad code that takes about 30 mins to calculate and it crashes often whenever I tried to change the axis limits. So, if there is a way to store latest calculated result so even after crash mathcad does not need to recalculate everything. I am importing and exporting data using insert>data>file input (or file output), so it is not a problem of saving data to or reading data from an outside file, but just that it would be nice that Mathcad does not crash or at least that I do not need to spend 30 mins to recalculate every time it crashes.

Many thanks in advance!

Newin

3 replies

V
24-Ruby III
VladimirN24-Ruby III
24-Ruby III
April 9, 2014

Before saving calculated document in main menu uncheck "Tools" -> "Calculate" -> "Automatic Calculation":

Pic_1.png

P
ptc-57822981-VisitorAuthor
1-Visitor
April 9, 2014

Hi Vladimir,

Thanks for your reply. However, this is not what I am looking for. What I am after is a way to not having Mathcad to 'lose' all its calculated result when it crashes or when I close it. Remove the auto calculation will just not doing any calculation (and no results) until I press F9 or Ctrl+F9.

What I woudl like to have is that the calculated data are there when I open Mathcad without needing to press F9 or activate automatic calculation.

Do you have any suggestion?

Cheers,

Newin

W
Werner_E25-Diamond I
25-Diamond I
April 9, 2014

Only way I can think of is that you save the calculated data yourself in a file (WRITEFILE, WRITEPRN, WRITEEXCEL,....) and read it in when opening the sheet again. As the sheet needs so long to do its calculations I guess you will have turned off autocalc anyway and evaluate expressions singly with F9, so on startup after a crash no recalc is done and you can manually activate the appropriate READ... command to get your data in.

M
MichaelH1-Visitor
1-Visitor
April 9, 2014

Which version of Mathcad are you using??

Try splitting your calculations into several worksheets and read/writing to data files to pass information from one worksheet to the next.

W
Werner_E25-Diamond I
25-Diamond I
April 9, 2014

The problem seems to be that its not the numerical data which should be preserved but the symbolic results, which cannot be saved to a file. So either rewriting the sheet to avoid the need for those symbolics or the manual copy and paste as Richard suggested seems to be the only options.

P
ptc-57822981-VisitorAuthor
1-Visitor
April 9, 2014

Is there a away to copy the equation that is a result of a symbolic calculation that Mathcad says is too large to display?

Newin

W
Werner_E25-Diamond I
25-Diamond I
April 9, 2014

Here is your demo file rewritten without using a single symbolic evaluation. I am sure it could be further streamlined and simplified - I simply strictly followed your sheet line by line.

The plot now takes quite a lot of time as the solve block has to be evaluated again for every of the 10^4 points plotted. So it might be a good idea to use precalculated symbolic results if possible (if they are not subject to change). See attached sheet for an example.

P
ptc-57822981-VisitorAuthor
1-Visitor
April 16, 2014

Hi Werner,

Thank you very much for the sheet and I am sorry that it has taken so long before I reply. I had a meeting last week and got drifted away early this week.

I am working on your sheet to extend it to my actual problem. However, I am stuck at this little problem of making a matrix as attached. I do not remember how it was made. I think Alan helped me doing that.

Anybod here know how to make such a 'nested' matrix? I need to put them all in one single equation for the solve box. OF course I could put them in one big matrix, but it would be nice to have it as in the attached for the reason of clarity.

Many thanks in advance,

Newin

PS

I am also trying what Richard said. However, the problem is that I can't copy and paste all the symbolic results because they are too long and Mathcad does not like to display it.

W
Werner_E25-Diamond I
25-Diamond I
April 16, 2014

Ad nested matrix: So you are still trying to use symbolics solve? You can't insert a matrix inside a matrix via Ctrl-M or the matrix creation button. Easiest way is to type the first equation somewhere on the sheet and copy and paste it to all five placeholders of the 5x1 vector. then edit the others to your needs.

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