jScope log y works but log x doesn't seem to work

[nelson-zapenergy]

Affiliation
Zap Energy

Question
I have a TDI-callable Python script called rfft.py that takes an MDSplus Signal Node from the Tree that is open, calls the SciPy rfft (fft of a real array, returns only positive frequencies), and returns an MDSplus Signal with the frequency as its dimension.

It works fine if I select "Log scale" for the Y axis, but if choose "Log scale" for the X axis (with or without "Log scale" selected for the Y axis) there are no data plotted. If I autoscale, I can drag the Point selection through the panel and the crosshairs seem to track where the Signal should be, as if it was plotted but with the same color as the background. I used rfft(\signame)[100e3 : 3e8] to assure there was not a zero value in the X axis, but I still get the same result, as if the Signal was plotted in a white color.

Any ideas?

Thanks,
Brian Nelson

[mwinkel-dev]

Hi @nelson-zapenergy -- Are you running jScope on a client computer or remotely on the MDSplus server?

Please provide more details about your configuration (operating system, MDSplus version, etcetera) and I'll see if I can reproduce the problem on my development system.

[nelson-zapenergy]

Thanks.

I'm running jScope on Windows 11 (MDSplus version "stable_release-7-131-6" from an mdsplus.org download) connecting to an MDSplus server with a compiled version of MDSplus and I get the following:

$ tdic
TDI> MdsShr->MdsRelease:T()
"stable_release-7-153-3"

Note that with Network set to Local, I can make the Y and X both [10 .. 1000], and selecting "Log scale" for Y, e.g.

I get:

With both Y and X selecting "Log scale":

I get:

If I select "Pan" and move the cursor around, I can get this momentarily:

But the line goes blank when I release the mouse button. If I select "Point", note that the crosshairs track along where the line should be, for example here:

and here:

[mwinkel-dev]

Hi @nelson-zapenergy -- Thanks for the additional detail. (Also, what version of Java do you have installed on Win11?)

Note that your Win11 client's MDSplus version, stable-7-131-6, was released on 3-Nov-2021.

I will first try reproducing the issue with a recent MDSplus release for Win11.

[nelson-zapenergy]

Thanks @mwinkel-dev !

java version "18.0.2.1" 2022-08-18
Java(TM) SE Runtime Environment (build 18.0.2.1+1-1)
Java HotSpot(TM) 64-Bit Server VM (build 18.0.2.1+1-1, mixed mode, sharing)

Should I upgrade either/both or wait?

[mwinkel-dev]

Hi @nelson-zapenergy,

Thanks for the Java version. I haven't tested jScope with that version, but my hunch is that Java 18 should be OK.

As general advice, yes it would be good to eventually upgrade your Win11 system to a recent MDSplus release. However, I cannot promise that it will solve your problems. (I've been busy fixing a bug for the Zap-HD system at Univ. of Washington so haven't yet had a chance to experiment with jScope.) My hunch is that the jScope issue you've encountered is likely present in recent releases too.

If this jScope issue is blocking your work and it is urgent to get it fixed ASAP, my suggestion is to use parallel tracks.

• You can upgrade your Win11 MDSplus immediately and see if that eliminates the problem.
• In the meantime, I will see if I can reproduce the issue using my development system.

Note that we split the Windows MDSplus release into a 32-bit version and a 64-bit version. If you do upgrade your Win11 client, be sure to use the 64-bit Windows installer. The most recent "alpha" release can be obtained either from the mdsplus.org website or from the "Releases" section of our GitHub site.
https://www.mdsplus.org/index.php/Latest_Windows_Distributions
https://github.com/MDSplus/mdsplus/releases

[nelson-zapenergy]

@mwinkel-dev no rush. It's a "nice-to-have" for log x scale. I am using the 64-bit MDSplus version, but I usually instale the "stable" version. So I am clear, are you suggesting I upgrade to the "alpha" version? Thanks

[mwinkel-dev]

Hi @nelson-zapenergy -- I am presently installing alpha-7-158-0 on my Win11 development system. In ~40 minutes, I will post to this issue whether the bug also exists in alpha. So, my suggestion is to wait until then before deciding whether to upgrade your Win11 client at this time or not.

The last stable release was stable-7-153-3 of 1-Jul-2025 and it does have the old combined 32-bit/64-bit installer. Which is why I recommend instead installing the alpha version. Recent alpha versions have a separate installer for 64-bit, and another installer for 32-bit. Furthermore, both installers now conform to Microsoft installation guidelines (i.e., no longer installs some MDSplus files in directories reserved for Windows).

[mwinkel-dev]

Hi @nelson-zapenergy -- I have just reproduced the problem in alpha-7-158-0. It is the same behavior described in your screenshots above. So, it makes sense to wait until we fix the bug before you upgrade MDSplus on your Win11 client.

[nelson-zapenergy]

@mwinkel-dev Thanks! Again, no rush on my side. I primarily wondered if I was seeing things. ;)