On 10/25/23 08:05, Zacharias-Panagiotis Oikonomou wrote:
*The problem seems to be that in a random timestep, the variable named
/temp /takes a NaN value, so I solved the problem with the if(isnan())
condition *(as shown below), but I was wondering if anyone has
encountered this problem and how they solved it.
Well, you didn't actually *solve* the problem, you just ignored it with
the if() statement :-)
The way to debug this is to figure out where the NaN came from. To
understand how to do this, note that you end up with a NaN value in your
right hand side vector. But you assembled that rhs vector. So in the
function that assembles the rhs, check every time you write something
(namely, a local contribution) into the vector, whether that something
is a NaN -- that's the only way a NaN can have gotten into your rhs vector!
When you have verified that the NaN gets into the vector through the
assembly, start looking through your assembly function and try to
understand how that NaN got there. Perhaps, you divided by zero
somewhere. Or you took the square root of a negative number.
Best
W.
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