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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Hey Adam,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Jan Wagner and Walter Brisken both offered to check, and concluded the segfault is a bug in 2.8.1 which was then fixed in the repo later. So the official 2.8.1 release
has a confirmed bug causing a segfault in vex2difx. Jan wrote: <br>
</span><span style="font-size:11.0pt;color:#1D1D1D;background:white">The fix was r10990 (trunk) and r10991 (2.8): "vex2difx.cpp fix segfault </span><span style="font-size:11.0pt;color:#1D1D1D"><br>
<span style="background:white">caused by missing realloc() of freqOffset[] and recFreqDestId[] - the </span><br>
<span style="background:white">associated code in vex2difx fixDatastreamTable() should really be moved into </span><br>
<span style="background:white">difxio".</span></span><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Pulling the trunk version sorted this, but there are other issues. Ufortunately, my attempts to correlate the data to get at my original problem – lack of fringes at
one specific baseline and polarisation combination – did not get further with 2.8.1 or trunk. My datastream formats get misinterpreted some how to wrong values, despite working with with 2.6.3 vex2difx. I tried some combinations of vex2difx, startdifx, and
difx2mark4 from 2.6.3 and 2.8.1 with –override-version but so far no solution. <o:p>
</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Simon C at OSO offered to look into the matter a bit more with the data we have, so I’ll await his findings and then maybe ask here again for additional advice.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Kind regards<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Eskil<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Adam Deller <adeller@astro.swin.edu.au><br>
<b>Date: </b>Sunday, 13 August 2023 at 13:03<br>
<b>To: </b>Eskil Varenius <eskil.varenius@chalmers.se><br>
<b>Cc: </b>difx-users@nrao.edu <difx-users@nrao.edu><br>
<b>Subject: </b>Re: [Difx-users] Lack of mixed-mode fringes with 2.6.3, then segfault with 2.8.1? {External}<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hey Eskil,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Have you tried vex2difx -v -v and/or valgrind vex2difx to see where the segfault is occurring? Obviously, it shouldn't be segfaulting, so presumably finding that and fixing it should go a fair way towards
solving the problem.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Cheers,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Adam<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">On Sat, 12 Aug 2023 at 04:22, Eskil Varenius via Difx-users <<a href="mailto:difx-users@listmgr.nrao.edu">difx-users@listmgr.nrao.edu</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Dear Difx-users,<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Background: I have mixed-mode continuum data from 3 stations: Ns(16 MHz VDIF), Ny(16 MHz M5B), Nn 32 MHz VDIF). Ns and Ny observe standard S/X with
R-pol only, and Nn (VGOS) observe dual linear X/Y (strictly speaking H/V but I'm using X/Y here since that's the VEX labels). Correlating Ns-Ny baseline with DiFX 2.6.3, is all good. I use zoom windows (to get 16 MHz from all stations) and FreqId selection
(to only correlate X-band and skip S-band channels). But when trying to correlate all three stations I run into problems.
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Problem 1: With DiFX 2.6.3 I can correlate all three stations, and then run difx2mark4. Fourfit then gives me nice fringes on the Ns-Ny baseline (R-R
pol), and the Ns-Nn baseline (RX and RY pol). But while I do get nice XR fringes on the Nn-Ny baseline, I do not get any YR fringes on this baseline. I know the data are good, since I get fringes to these polarisations on another baseline. So I suspect I have
fallen into the "Warning: Limited support for mixed-mode..." here, or do you have other suggestions?
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">I saw there are improvements for mixed-mode in DiFX 2.8.1, so I decided to try it, but:<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Problem 2: With DiFX 2.8.1, I get "segfault" when I run
</span><span lang="EN-US" style="font-size:11.0pt">”</span><span style="font-size:11.0pt">vex2difx</span><span lang="EN-US" style="font-size:11.0pt">” (this worked with 2.6.3)</span><span style="font-size:11.0pt">. Any ideas?<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">I guess hunting the "segfault in 2.8.1" is the most profitable route for the future? If so, please let me know what info you may need to speculate
further. I am happy to share output, v2d, vex, and even raw data for one scan for someone to reproduce this if you would be so kind to help.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">I am very puzzled by this!<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Kind regards<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">Eskil<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">_______________________________________________<br>
Difx-users mailing list<br>
<a href="mailto:Difx-users@listmgr.nrao.edu" target="_blank">Difx-users@listmgr.nrao.edu</a><br>
<a href="https://listmgr.nrao.edu/mailman/listinfo/difx-users" target="_blank">https://listmgr.nrao.edu/mailman/listinfo/difx-users</a><o:p></o:p></span></p>
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<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span class="gmailsignatureprefix"><span style="font-size:11.0pt">--
</span></span><span style="font-size:11.0pt"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">!=============================================================!<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">Prof. Adam Deller <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">Centre for Astrophysics & Supercomputing <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">Swinburne University of Technology <br>
John St, Hawthorn VIC 3122 Australia<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">phone: +61 3 9214 5307<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">fax: +61 3 9214 8797<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.5pt">!=============================================================!<o:p></o:p></span></p>
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