[ncl-talk] question regarding Butterworth filter

[Dennis Shea]

There is nothing 'special' being done at the series end.

A copy of the f90 code used will be provided to you for your perusal.

Cheers


On Mon, Jun 15, 2015 at 11:51 AM, Daniel Barandiaran <dbarandiaran at gmail.com
> wrote:

> Hi everyone,
>
> I was trying out the bw_bandpass_filter function and found some unexpected
> results. The gist of the problem is that the end of the time series being
> filtered approaches a smoothed zero, even if the time series is doing
> something else entirely (see attached figure, consider bold blue line and
> shaded blue area). I imagine this is due to the internal workings of the
> filter itself, but regardless of that, does anyone have any ideas on
> "fixing" this?
>
> Some details: I have fca set to 1/60., or 5 years, and fcb set arbitrarily
> large, i.e. 1/100000., so the filter essentially behaves as low pass. I am
> also making sure to not give the function any missing values.
>
>
> --
> Danny Barandiaran
> Ph.D. Candidate
> Department of Plants, Soils, and Climate
> Utah State University
>
>
>
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