Raph,
I have to admit to being a little dense at first on this one
(per my previous post), but I finally realized what the Collector is
doing,
and how it can be used to constrain the autocorrelation sequence
returned by the function (as opposed to passing in a parameter,
as in the proc I had defined).
For my current problem, I want all of the values returned in the
sequence to
be the same. However, for other problems, I may want to constrain that
sequence of values differently.
So, allowing the Autocorrelate function to collect results in a vector,
and then separately constraining the results is more flexible/general
purpose.
Once I realized this, and called it properly (see the snippet),
everything works as I expected.
---------- snippet ---------------------
AutoCorrelationSequence = {Autocorrelate {Append [0] {Record.toList
Histogram}}}
for S in AutoCorrelationSequence
do
S=: (2*T - 1)
end
----------end snippet-------------------
Thanks again for your help!
George
> >
> > {Autocorrelate Count (2*T - 1)}
> >
> > It fails with a red square, as opposed to a light green diamond.
> >
> >
> > ---------- begin code ------------------
> > proc {Autocorrelate Xs Val}
> > NumberOfShifts = {List.length Xs} - 1
> > in
> > for I in 1..NumberOfShifts do
> > %rotate the list Xs by: splitting the list at position I
> > %then slicing the list back together with the parts swapped
> > CopyOfXsRotatedISlots={Append {List.drop Xs I} {List.take Xs I}}
> > Matches={List.zip Xs CopyOfXsRotatedISlots fun {$ X Y} X=:Y end}
> > in
> > {FD.decl Val}
> > {FD.sum Matches '=:' Val}
> > {Browse Matches}
> > end
> > end
>
> George, you are constraining *all* the shifted dot products to be
equal
> to Val. Is this what you meant?
>
> You can make Autocorrelate return a list of the products by using the
> 'collect' feature of the for loop as:
>
> fun {Autocorrelate Xs}
> NumberOfShifts = {List.length Xs} - 1
> in
> for
> I in 1..NumberOfShifts
> collect:Collect
> do
> %% rotate the list Xs by: splitting the list at position I then
> %% slicing the list back together with the parts swapped
> CopyOfXsRotatedISlots={Append {List.drop Xs I} {List.take Xs
I}}
> Matches={List.zip Xs CopyOfXsRotatedISlots fun {$ X Y} X=:Y
end}
> Val
> in
> {FD.decl Val}
> {FD.sum Matches '=:' Val}
> {Collect Val}
> end
> end
>
>
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