On Wed, Oct 7, 2009 at 4:39 PM, Brian Granger <ellisonbg....@gmail.com> wrote:
>
>
> On Wed, Oct 7, 2009 at 4:19 PM, Ondrej Certik <ond...@certik.cz> wrote:
>>
>> On Wed, Oct 7, 2009 at 3:46 PM, Brian Granger <ellisonbg....@gmail.com>
>> wrote:
>> > Øyvind,
>> >
>> > It will take me a while to go through everything, but I just read
>> > through
>> > some of it quickly. It all looks quite
>> > powerful and nice. One minor thing and one question:
>> >
>> > * In various places you use the variable "str." This is dangerous as
>> > str is
>> > a builtin type (a string).
>> >
>> > * It is a little awkward to have the occupation #'s stored differently
>> > for
>> > bosons and fermion. For bosons
>> > it looks like you store the list of occupation #'s (dense format) but
>> > for
>> > fermions, the indices of occupied states
>> > (sparse format). Did you do this for performance/algorithmic reasons?
>> > For
>> > states with a few particles but many states the sparse
>> > structure of your fermionic approach would be better, but as the number
>> > of
>> > particles approaches the number
>> > of states, I think the sparse format doesn't give any advantage. I am
>> > wondering if we can use the same
>> > storage format for both bosons and fermions. Sparse for both? Dense
>> > for
>> > both?
>> >
>> > * Am I correct that you are using assumptions to keep track of whether
>> > or
>> > not an index is above or
>> > below the fermi surface. Are you using the new assumptions system? I
>> > haven't followed this very
>> > closely - Ondrej can you comment on which should be used?
>>
>> Currently the old system, and once we finish the new system, the new
>> system should be used.
>>
>> However, this:
>>
>> + �...@property
>> + def is_above_fermi(self):
>> + """
>> + Does the index of this FermionicOperator allow values above
>> fermi?
>> + """
>> + return not self.args[0].assumptions0.get("below_fermi")
>>
>>
>> will cause problems, because the new assumption system doesn't store
>> the assumptions within the symbols. One could use global assumptions,
>> or remember them locally in the instance though and the new system
>> should allow to create new assumptions easily.
>>
>> Why not to store this information in the FermionicOperator(SqOperator)
>> instance itself? (And not use assumptions at all?)
>>
>
> But doesn't this seem like a good application of assumptions?
I guess it is. I am just pointing out to make it easy to port to the
new assumptions system.
Ondrej
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