Hello,
I am typesetting a table with pgfplotstable and stumbling over some
weird rounding mistakes, seemingly on the part of pgfplotstable. Any
help is appreciated.
I am calculating some "energy" that should converge to the correct value
at some specific "level" (see example below). In order to asses this
convergence I calculate the absolute difference between the "energy" on
this specific "level" against the "energy" on current one "level".
I notice some weird rounding mistakes in the table values that I cannot
explain: The "diff" value of "level" 6 should read (at least) 1.e-5 not
2e-5, if not even -313.3008711--313.3008819 = 1.08e-5.
I am using pgf version 2.10-cvs and updated to pgfplots 2012/08/23
v1.6.1 (git show 1.6.1 ) (downloaded today from sourceforge), both
version numbers are taken directly from the pdflatex log.
On a further note: I searched the (excellent) manual, stumbling over
/pgfkeys{/pgf/fpu=true}. However, as the fpu is always activated when
using "expr" this does not seem to be the issue?
Here is the minimum example (sorry for the messy table creations but I
don't want to bother you with files, it's the same result anyway):
======================= SNIP ===========================
\documentclass{article}
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\begin{document}
Here is a minimum example:
% just create a list of example values
\pgfplotstableset{
create on use/a/.style={create col/set list={1,2,3,4,5,6,7}},
create on use/b/.style={create col/set
list={-321.4430756,-313.2926882,-313.3037961,-313.3012453,-313.3008931,-313.3008819,-313.3008711}},
}
% create the table
\pgfplotstablenew[columns={a,b}]{7}\supertable
% get the minimum value from level "7" (index starts at 0)
\pgfplotstablegetelem{6}{b}\of\supertable
\let\amin=\pgfplotsretval
% prepare creation of one more row "diff" that is the absolute
difference between the minimum value and the current one
\pgfplotstableset{
create on use/diff/.style={
create col/expr={
abs(\amin-\thisrow{b})
}
},
}
% create the complete table with the difference column
\pgfplotstablenew[columns={a,b,diff}]{7}\moresupertable
% print the table
\pgfplotstabletypeset[
columns={a,b,diff},%
columns/a/.style={
column name={level},
precision=6,
},
columns/b/.style={
column name={energy},
precision=6,
},
columns/diff/.style={
column name={diff},
precision=6,
},
]{\moresupertable}
\end{document}
======================= SNIP ===========================
Regards and thanks,
Frederik
--
Dipl.Phys. Frederik Heber
Wegelerstrasse 6/5.011, 53115 Bonn
Tel.: +49 228 73 3866
(Arbeitsgruppe Prof. Dr. M. Griebel)
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