[Patch] reworked advanced-portfolio.scm

[Andrew Sackville-West]

On Sat, 18 Feb 2006 15:44:38 -0500
Derek Atkins <warlord at MIT.EDU> wrote:

> Make sure you're responding to the list, please....

heh. you too ;)
> 
> Quoting Andrew Sackville-West <andrew at farwestbilliards.com>:
> 
> >> E.g., here's a problem case:
> >>
> >>   Buy 100 shares on date T0
> >>   pricedb entry on date T1
> >>   pricedb entry on date T2
> >>   Sell 50 shares on date T3
> >>
> >> Let's assume that delta-t is something like a week or a month, or even
> >> a year.  The value of the sale at T3 could be VERY DIFFERENT than the
> >> value in the pricedb at time T2.  When looking at the value of your
> >> holding at time T4, IMHO you should use the price from time T3, not
> >> the price from time T2.
> >>
> >> Perhaps we need some C code to make this easier to compute "on the
> >> fly".  But it's IMHO how it should work.
> >
> > yeah, I understand now. good example. So the issue I see is that we
> > have to get away from exchange-fn altogether as that is what breaks
> > without a pricedb. AM I right? So I have to come up with some other way
> > of converting the currencies. The real problem here is that I just
> > don't understand what Mike's patch was supposed to do in the first
> > place. All I did was fix it so it ran :). Alright, I'm off to study
> > this thing more closely and see if I can figure out the proper way to
> > do it. I'll report back captain.
> 
> I'm not sure we have to get away from exchange-fn altogether..  Although
> we might need to extend it a bit.  The current exchange-fn is defined in
> report-system/commodity-utilities.scm : gnc:case-exchange-fn and returns
> a procedure that does the computation.   There are some docs there in
> the source file.

yeah. more study comin' up.
> 
> I'm not convinced the problem here is exchange-fn.  I think the problem is
> partly that we're assuming a price-db earlier and creating bad commodity
> collectors.

makes sense.
> 
> I'm hoping Mike will chime in and explain to you what he was trying to do.

Me Too!

A
> 
> You're always welcome to pull out a particular version of the report from
> SVN.  http://svn.gnucash.org/trac/browser
> 
> Good Luck,
> 
> -derek
> -- 
>        Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
>        Member, MIT Student Information Processing Board  (SIPB)
>        URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
>        warlord at MIT.EDU                        PGP key available
> 
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