DPlot

Hello David --

In reviewing the Help file under "Differentiate a Curve (Generate menu)" the description includes this phrase:

"The "Curve(s) to operate on" box contains a list of all curves ... "

Where does on find this 'box' ?

Version 2.3.5.3 Thanks, --len

BTW - I did get the macro Differentiate to work as a work around.

I just noticed what is refereed to as the "Curve(s) to operate on" box is no longer popping up in DPlot. I tried Delete Curve on a plot with to curves but no popup box appeared.

This is a new phenomena as things were working fun just two days ago, i.e. no update was applied.

Any ideas? --len

After more testing the lack of a curves popup box seems related to using the Differentiated Curve menu item.
Before selecting this menu item the Erase Curve generates a popup dialog, but after issuing a Differentiated Curve menu - no popup appears for any subsequent command. --len

The list is limited to curves that are monotonically increasing in X. If you only have one curve that does that, then the list will be disabled and that one curve is selected by default. If you have NO curves that increase in X then the command would be disabled.

If this doesn't agree with what you're seeing, please save a graph as a DPlot file and send it to me.

After more testing the lack of a curves popup box seems related to using the Differentiated Curve menu item.

If that really is the case then something has gone badly haywire. My best suggestion is to exit DPlot, reboot, and try again.

DPlot example file sent

Open the attached DPlot
Check that Erase Curve shows two curves – but do not erase
Use Differentiate Curve menu item
No popup curve box appears?
Check that Erase Curve shows two curves – no popup box appears.

Is it me of DPlot ?

Thanks, --len

Thanks for the file. There's definitely a bug that I need to look into, but it can be worked around by first sorting your two curves (Edit>Sort, and they both need it). What should happen with your unedited data is Generate>Differentiate should be disabled and/or present an error message telling you why you can't use it.

But that doesn't explain why subsequent commands like Erase should fail. Something is amiss.

This is now fixed, and the fix will be included in the next release. Thanks for pointing out the problem.

Thanks David for having a look.

I was surprised the Edit>Sort was needed for my data - I believe the x-data was monotonically increasing. In any case, the Generate>Differentiate then worked.

However, the resulting derivative plot ends with a large +/- spike that essentially obscures the other values of the derivative.

--len

I was surprised the Edit>Sort was needed for my data - I believe the x-data was monotonically increasing.

That's easy enough to tell if you import the data into Excel and add a column with, for example, =if(A2<A1,1,0).

I should probably add a command to report this condition.

However, the resulting derivative plot ends with a large +/- spike that essentially obscures the other values of the derivative.

The answer is correct, though. It is due to the large spikes near the end of the record. Zoom in and you'll see. You might be happier with first using Edit>Equal Intervals on the input.

Thanks David for your help and the useful information about a few of the many features of DPlot. --len