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spFactor error: Zero Diagonal

Posted: Wed May 21, 2008 12:35 pm
by mjb7
I received the following error during simulations of extracellular stimulation using the extracellular mechanism:

"spFactor error: Zero Diagonal"

This only occurs when the stimulation amplitude is sufficiently high. I'm pretty sure it has something to do with the large extracellular potentials created by the stimulus, and hence extremely large and rapid fluctuations in the transmembrane potential as compared to those produced physiologically. I went through all of my .mod files and hard-coded in catches for extremely large exponents and/or singularities. Any other ideas as to what might be the cause of such an error?

Thank you!

Posted: Thu May 22, 2008 9:42 am
by ted
Can you reproduce the problem with a model that has simpler membrane properties? e.g.
eliminate all but the major spike currents and see if the symptom can be elicited.

Re: spFactor error: Zero Diagonal

Posted: Tue Mar 13, 2012 2:00 am
by dearambellina99
Hi,

Can someone please explain the nature of this error? I dont understand its behavior. Unlike the OP, I receive the error at certain values of e_extracellular -- not necessarily past a threshold. For example, when my stimulus is 2.49 or 2.51 mA, the simulation runs fine. When the stimulus is 2.50 mA, the simulation breaks.

The complete error is:

"/Applications/NEURON-7.2/nrn/i386/bin/nrniv.app/Contents/MacOS/nrniv: spFactor error: Zero Diagonal
near line 23
hoc_ac_ = istim
^
fadvance()
advance()
step()
continuerun(2.5)
and others"

Thank you.

Re: spFactor error: Zero Diagonal

Posted: Wed Mar 14, 2012 2:16 pm
by hines
I'd like to reproduce these errors and try to diagnose the underlying reason. Can each of you
send me a zip file that contains the hoc,ses,mod files needed along with how to run so that the
error occurs. Please send to michael dot hines at yale dot edu.