Debugging NEURON MOD files?

Question

What are some useful ways to debug NEURON simulator .MOD files? In other languages one can usually use print() statements to see the variable values. Is there something like a print() statement in .MOD files?

Answer 1

Use printf() statements

For example, in any of the sections within a .MOD file, adding the printf() statement below will print the variable t, i, and v values every time that section is evaluated during the simulation:

BREAKPOINT {
    SOLVE state METHOD cnexp
    g = (B - A)*gmax
    i = g*(v - e)

    printf("time: %g, current: %g, voltage: %g \n", t, i, v)
}

Will result in something that looks like this:

time: 231.062, current: 0.000609815, voltage: -67.2939 
time: 231.188, current: 0.000609059, voltage: -67.2938 
time: 231.312, current: 0.000608304, voltage: -67.2937 
time: 231.438, current: 0.00060755, voltage: -67.2936 
time: 231.562, current: 0.000606844, voltage: -67.2924 

Notes:

• Recompile the .mod files in the folder after adding the above statements
• Don't forget to include the '\n' at the end to avoid piling up the output
• Other parameter options (besides %g) can be found in the printf() reference