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Ninetrees3-Newcomer
3-Newcomer
March 28, 2010
Question

Mathcad 14.0 M020 (14.0.2.5) 2D plot questions

  • March 28, 2010
  • 9 replies
  • 4027 views
I searched the collab for a clue to this because it seems that I have seen it discussed previously. Didn't strike paydirt.

I had some step plots that I was using - many of them. I got tired of resetting the index variable

i:=last(table)
x:=1 x[i:=i

so I changed to using the method in the attached file. I didn't get the result I expected.

Is there a way to get the plots I want with out having to reset the x index all the time?

Rich
http://www.downeastengineering.com/

9 replies

TomGutman1-Visitor
1-Visitor
March 28, 2010
Quickplot (using an undefined variable for the ordinate) is for plotting functions, not discrete values. The implied range for the ordinate is not integers, so using it as a subscript results in many errors, hence a discontinuous graph. You can use a range variable or a vector for the ordinate, but you must set it up yourself, so that the values are the integer indices for the data.
__________________
� � � � Tom Gutman
Ninetrees3-NewcomerAuthor
3-Newcomer
March 29, 2010
Well, that helps a lot. Thanks, Tom. It also showed me how to save some steps in the file that I am working with, so I'll make those corrections in the next day or so. I have excerpted a few items because I have a question about them: Why does the step plot work in one place and not the other? I'm guessing that I am missing some implication of your earlier post. Sorry to others for my post in M14, but I suspect that my issues are M14 questions.





Rich


http://www.downeastengineering.com/
TomGutman1-Visitor
1-Visitor
March 29, 2010
Your issues have nothing to do with MC14 -- just the way quickplot works.

Your first graph appears to work. Your range is from 0 to 2000. Divided into 1000 steps (the way quickplot works) you get an effective step size of two. All ordinate values are integers and work as subscripts. But you are only seeing every other point.

You second plot has a much reduced range, and in a thousand parts just about none of the values are valid indices. Hence no plot.

I reiterate -- quickplot is for plotting functions, not discrete data. If you persist in attempting to use quickplot with discrete data, you will run into all kinds or errors and anomalies. Don't do it.
__________________
� � � � Tom Gutman
ptc-13682881-Visitor
1-Visitor
March 31, 2010
On 3/28/2010 11:02:30 AM, woodwise wrote:
...
>Is there a way to get the
>plots I want with out having
>to reset the x index all the
>time?
>
>Rich
_____________________________

YES, use my traditional discretizer.
Attach your ws 11 if you wish.

jmG


mzeftel1-Visitor
1-Visitor
April 2, 2010
This has been logged for documentation for Mathcad 14 and 15. I don't know if the same issue is true in Mathcad Prime, since the 2D plots differ, but I will check.

Mona
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