The documentation is not all that clear about the procedure to follow,
when using the Python interface. I'd like to call a function like:
def esq_mag(r, ex, ey, ez):
return ex*ex.conjugate()+ey*ey.conjugate()+ez*ez.conjugate()
from the at_every construct - I initially used the above function
together with:
sim.run(mp.to_appended(prefix, mp.at_every(0.1,
sim.output_field_function('E_sq', [mp.Ex, mp.Ey, mp.Ez], esq_mag))),
until=t)
but the program runs to the point where output is triggered, then stops
with a lengthy error message, terminating:
File "/usr/lib/python3.6/site-packages/meep/simulation.py", line
28, in get_num_args
return func.__code__.co_argcount
AttributeError: 'NoneType' object has no attribute '__code__'
That does not surprise me as the docs state I have to pass a function to
the sim.run function, not the result of evaluating a function. So I
tried again, supplying in the spirit of the instructions related to
Scheme "a function |my-weird-output| of no arguments that, when called,
outputs our function |f|." So I constructed a function to do that:
def esq_mag():
def _esq_mag(r, ex, ey, ez):
return ex*ex.conjugate()+ey*ey.conjugate()+ez*ez.conjugate()
return _esq_mag
but the result is another error:
TypeError: esq_mag() takes 0 positional arguments but 4 were given
OK - I need to handle those arguments to esq_mag, so
def esq_mag(r, ex, ey, ez):
def _esq_mag(r, ex, ey, ez):
return ex*ex.conjugate()+ey*ey.conjugate()+ez*ez.conjugate()
return _esq_mag
but now the program fails with:
TypeError: must be real number, not function
The above exception was the direct cause of the following exception:
SystemError: PyEval_EvalFrameEx returned a result with an error set
I have tried several variations without success; please, what construct
should I be using?
Also, if I try to use output_real_field_function as described in the
docs, I get the error:
AttributeError: 'Simulation' object has no attribute
'output_real_field_function'
I'll be very grateful for any help,
Ian
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