Hi Troels,
Here is one suggestion, of many that I have, for significantly
improving the speed of the analytic dispersion models in your
'disp_spin_speed' branch. The speed ups you have currently achieved
for spin clusters are huge and very impressive. But now that you have
the infrastructure in place, you can advance this much more!
The suggestion has to do with the R20, R20A, and R20B numpy data
structures. They way they are currently handled is relatively
inefficient, in that they are created de novo for each function call.
This means that memory allocation and Python garbage collection
happens for every single function call - something which should be
avoided at almost all costs.
A better way to do this would be to have a self.R20_struct,
self.R20A_struct, and self.R20B_struct created in __init__(), and then
to pack in the values from the parameter vector into these structures.
You could create a special structure in __init__() for this. It would
have the dimensions [r20_index][ei][si][mi][oi], where the first
dimension corresponds to the different R20 parameters. And for each
r20_index element, you would have ones at the [ei][si][mi][oi]
positions where you would like R20 to be, and zeros elsewhere. The
key is that this is created at the target function start up, and not
for each function call.
This would be combined with the very powerful 'out' argument set to
self.R20_struct with the numpy.add() and numpy.multiply() functions to
prevent all memory allocations and garbage collection. Masks could be
used, but I think that that would be much slower than having special
numpy structures with ones where R20 should be and zeros elsewhere.
For just creating these structures, looping over a single r20_index
loop and multiplying by the special [r20_index][ei][si][mi][oi]
one/zero structure and using numpy.add() and numpy.multiply() with out
arguments would be much, much faster than masks or the current
R20_axis logic. It will also simplify the code.
Regards,
Edward
Speed up suggestion for task #7807.