Debugging C mex - jvm.pdb not loaded exception

Hi, I hope you can help.

I'm confused by the sporadic read access exceptions during debugging C mex code with Visual Studio 2019 (v16.9.1) and Matlab R2020b. I appear to be getting read access exceptions at different times during stepping through the code. At first I thought it was my code, but I'm getting the exceptions on one trial, but I can step over the same code on the next try sans error (no random numbers here, identical every time data and code wise). I get a No Symbols Loaded tab pop up in the VS window (see below) that informs me that the jvm.pdb is not loaded.

I think I might (correction, do, just found it) have an issued with the second loop in my code, but these sporadic read exceptions are making things really hard to debug.

I've attached a mat file and a notes m file. If you change the path to load the mat file and step through you can see my working. Matlab crashes each time I get an exception, so I typically load Matlab, run the first four sections, attach to matlab in VS2019, select the break point and then run the 5th section of the m file to jump in. Line 94 in the c code (in the zip) is a good place to jump in.

Any misc tips on my first c code and mex file much appreciated (Note this code is ported from https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-23-25-32387&id=333299 who kindly sent me their code; while I love Igor Pro, it's too esoteric to be practical when sharing and it needed to be brought over to Matlab)

Thanks

Neil

[N R Anthony]

Here's an example of the Exception Thrown on a line in debugging that's well before any actual errors should be thrown:

Exception thrown at 0x00000000567E8598 (jvm.dll) in MATLAB.exe: 0xC0000005: Access violation writing location 0x0000011B8ED70780

This time it happened just entering the first for loop.

[Joe Lillig]

I have this same problem. Is there a solution?

[N R Anthony]

Kinda...

I found that when I just kept on stepping on throught the code, these errors would occur, but not stop things. Sometimes I see them and sometimes I don't, but in retrospect, I think they can be ignored. Not really sure, but I managed to debug things that way.

Good luck with the code.

Neil