Andrew Hassal wrote:

>> I'm writing 2 externals that implement an LPC algorithm, to make the
>> results as acurate as possible I need to record some values from the
>> previous frame, I've found that after doing this I sometimes as far as
>> I can tell randomly get the output values of nan (for the values in
>> the output signal vector) 

...

Did you already find the answer? The fact that the problem specially arises when you open a patch with a graph in it, may indicate that your code is accessing memory locations which are not allocated to it. Stand alone executables would by definition exit with segmentation fault, but with Pd externals I have experienced more than once that the problem was only revealed in a conflict with another object in the Pd process, notably when using multiple instances of the newly written class.

Katja