Set the chunksize used by LAMA for partitioning the data array. This must be smaller than an upper limit determined by the free memory factor, which is the fraction of memory kept free as a temporary workspace, otherwise an error is raised. If called with None as the argument then the chunksize is set to its upper limit. If called without any arguments the existing chunksize is returned.

The upper limit to the chunksize is given by:

upper_chunksize = ((free_memory_factor * TOTAL_MEMORY()) / ((mpi_size
chunksize: float, optional

The chunksize in bytes.

out: float

The previous value of the chunksize in bytes.