Complex Plotting - What is Default?

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Mon, 08/17/2015 - 06:32 am

Hi,

When I plot complex waves, I get some hybrid that I don't find very useful. What is the default plotting style that I'm seeing, and can I change it?

Thanks.


(See picture).
On the Igor command line, execute:
DisplayHelpTopic "ModifyGraph for Traces"


Then scroll down a bit to the explanation of the cmplxMode keyword.

That data browser is effectively plotting your data twice. The red line is the real component, and the blue line is the imaginary component. You can get the same effect in a regular plot buy appending the wave to the plot twice. Set cmplxMode to 1 for the first trace and cmplxMode to 2 for the second trace (and set the color of the second trace to something other than red).

Note that you can set the cmplxMode for a trace from the Modify Trace Appearance dialog.

August 17, 2015 at 08:22 am - Permalink

I can work with the plots once they're generated, but my question is why is the default feature as shown? I don't find it useful...I would find either real + imaginary plotted simultaneously, or simply magnitude to be good defaults (or even all three). But what's shown on the left plot I posted isn't useful...I have to change it 100% of the time. If there's no way to change the default, maybe I'll post that as a suggestion.

August 17, 2015 at 08:40 am - Permalink

As the help for ModifyGraph cmplxMode says, "Default mode displays both real and imaginary parts (imaginary part offset by dx/2)."

I don't know why that was made the default originally, but that can't be changed now without breaking old experiments that rely on that default behavior.

August 17, 2015 at 01:32 pm - Permalink

That's right- the graph shows your data as if the data set were real0, imaginary0, real1, imaginary1, ... The sawtooth effect is from the lines-between-points mode connecting all those reals to imaginaries to reals, etc., in a graph that isn't very useful. As ACLight says, it would be nice if we could change the default...

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

August 18, 2015 at 09:23 am - Permalink

Ok, that makes sense. Not sure how long it would've taken me to figure that out. Is there maybe a way to add in a modified default, with a warning for users with older experiments?

September 3, 2015 at 08:51 am - Permalink

I just tried capturing the complex display mode as a preference- it seems it is not included in the preferences. I have added this to the Wish List.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

September 3, 2015 at 10:03 am - Permalink

The complex display mode is now captured to graph preferences in Igor 7.

September 14, 2015 at 11:17 am - Permalink