topic Re: Solve in Mathcad

Solve

eng.gdal — Wed, 12 Apr 2023 15:37:02 GMT

Hi I have a problem to show my results in a table where the column will be given "t" and the rows will be "Pwf". If there's anyone who can help me, please. In the picture I use only t_0 in the formula and I would like to use all values immediately and present the result in the matrix 4x11, help me, please

Re: Solve

LucMeekes — Wed, 12 Apr 2023 17:18:34 GMT

Please attach your (Prime) worksheet file. That will allow us much better to help you.

By the way. Prime 'knows' the Euler constant:

Success!
Luc

Re: Solve

Werner_E — Wed, 12 Apr 2023 17:58:11 GMT

Use the last formula for q0, which, as I think, should be the first column of your table.

use a double matrix index on the left hand side

and replace on the right hand side the variable P.wf by P.wf[i (P.wf with vector index i).

Or even better, simply replace the whole expression in parentheses (P.i-P.wf) by P.i*0.1*i

Variable q should now hold the table you are asking for.

Re: Solve

eng.gdal — Wed, 12 Apr 2023 18:22:09 GMT

Great advice on Euler's constant! Thank you very much. I am uploading my working file with my problem.
Sincerely, Kacper

Re: Solve

eng.gdal — Wed, 12 Apr 2023 18:34:05 GMT

Thank you very much for your suggestions, I tried something with your proposal but the results came out as I want for all time periods but only in one column.
Greetings

Re: Solve

Werner_E — Wed, 12 Apr 2023 20:12:30 GMT

Can't debug a picture!

Problem seems to be that you like to use inline evaluations. By this I mean that you follow a definition immediately by an evaluation (=) like
x:=<calculatong term>= ...

While this is allowed it can sometime lead to unexpected and undesired results. Ist better to separate definition and evaluation:

One region: x:=<calculatong term>
and in a second region the evaluation x = ...

I guess that if you evaluate q in your sheet you would see a nice table (but with columns and rows exchanged).

Here is what I was talking about

Prime is not good in creating nice row and column headers and while its allowed to have quantities in different dimensions/units in one matrix, you are not allowed to change the units inside of the matrix and are restricted to the default units. Which means that you would see the time in seconds and not in years, etc.

Therefore in the following table I removed the units completely

Worksheet (P9) attached

Re: Solve

eng.gdal — Thu, 13 Apr 2023 15:18:54 GMT

Great solution! Thank you very much for such a comprehensive and well written solution to my problem 😁. I will definitely use it in the future, again Thank you and I'm closing the post.