Hello Carsten,
I was adapting org-mode to my applications when I noticed that it
could
not add up! I had a table in which one column was a column of
figures,
and I wanted the sum, and org-mode came up with the wrong answer. I
was
flabbergasted when I discovered that this behaviour was documented
as a
feature!
Specifically, the offending line was
calc-float-format (float 5)
Apparently, if the calc default of 12 were used, the tables could look
ugly, so it was thought better to produce a pretty table than a
correct
one!
At first I thought that this might be merely a display problem, that
internal calculations would be more accurate, and that I could get the
extra precision that I needed using a printf style print, but no. The
printed value indeed had an extra digit, but that right most digit
was a
meaningless '0'.
I've changed this in my .emacs file, but I would urge a re-think on
this.
As a numerical analyst, I feel comfortable with rounding errors, and
precision, and I accept that it is impossible to supply exact
answers to
all calculations, but working with only decimal 5 digit precision I
find
rather frightening. (How calc came up with a default of 12 I don't
know; it's capable of arbitary precision, but anything less that the
precision of a double precision of 64 bits (about 16 decimal places),
and all the paraphernalia of guard digits etc. that the hardware
floating point units use is odd.)
Perhaps a line like
#+PRECISIOM 21
would be nice so that the user can choose his precision on file by
file
basis, and keeping the above value at 12, the calc default. I sixth
digit after a decimal point for a tax return is clearly too much, but
for financial calculations involving millions, this would be
unacceptable. It follows that this really should not be hard coded,
but
set on a file by file basis.
I don't want to sound negative, though; org-mode is really nifty, and,
although I have still to get into it properly, I have great
expectations
that I am sure will be fulfilled beyond all my hopes! Great work!
Cheers,
Mike Dowling
--
Dr. Michael L. Dowling
Gaußstr. 27
38106 Braunschweig
Germany