- If it crashes and I immediately re-run with the same inputs it always goes on crashing.
- If I then run with different inputs it may work correctly.
- If after doing something else I re-run with the original inputs that caused the crash it may work correctly.
- Changing the layout of code, or changing nearby code, may change it between working and crashing. E.g. I originally had if nargin>4, it = it0; end below, and changing it to what's written cured the problem – so I thought! But it reappeared with other inputs.
- Stepping through in the debugger, with argument it0 absent so nargin>4 is false, I found that though it skipped the it = it0; statement, it nonetheless changed the value of it to an unpredictable value (e.g. 165) while going from if to end.
- Once past this perilous initialisation, it seems it behaves as it should do.
Bug in Persistent variables? Simulink M-function
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I am unable to initialize a Persistent variable. Here's a snippet of code in a Simulink M-function which does not actually set 'a' no matter what I do:
persistent a
if isempty(a)
a = 1;
end
Either printing out 'a' or evaluating 'a' gives
a=[]
...NOT a=1 as it should.
It doesn't matter what the variable name is, or what I try to set it to, or how many variables there are. This bug happens with two different sets of Persistent Variables.
However, oddly, later on in the SAME M-function, I do another persistent declaration using the exact same method and there initialization DOES work.
I tried this in both R2016a and 2017b
What is going on?
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