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Groups > comp.graphics.apps.gnuplot > #315

Multible Fits using the same fit function lead to ?false? results.

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Hi
i just noticed that using a gnuplot script like this:
fit a0 + a1*(1/x)**2 + a2*(1/x)**4\
'<grep -v \# table.dat  |awk "\$1 =="10" {print 1,\$2} \
\$1 =="10" {print 2, \$3}\
\$1 =="10" {print 3, \$4}\
\$1 =="10" {print 4, \$5}"'via a0,a1,a2
print "value a0 ",a0

fit a0 + a1*(1/x)**2 + a2*(1/x)**4\
'<grep -v \# table.dat  |awk "\$1 =="20" {print 1,\$2} \
\$1 =="20" {print 2, \$3}\
\$1 =="20" {print 3, \$4}\
\$1 =="20" {print 4, \$5}"'via a0,a1,a2
print "value a0 ",a0

fit a0 + a1*(1/x)**2 + a2*(1/x)**4\
'<grep -v \# table.dat  |awk "\$1 =="30" {print 1,\$2} \
\$1 =="30" {print 2, \$3}\
\$1 =="30" {print 3, \$4}\
\$1 =="30" {print 4, \$5}"'via a0,a1,a2
print "value a0 ",a0

on a table.dat file like this (just an example):
#x     y1     y2     y3
10     12     43     42
20    234    324   33
30     3         3       3

leads to false results, i have to reset (or set to zero) die
coefficients a0, a1, a2 after/before every fit by placing
a0=0
a1=0
a2=0
before each fit block in the gnuplot script.
If i do not do this the last values for the coefficients are taken
into the next fit and this is influencing the results.

The problem is the influence, because i do not know why this is so,
and setting them to zero is just one way i could use other values too!

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Multible Fits using the same fit function lead to ?false? results. Oliver Götze <goetze.oliver@googlemail.com> - 2011-05-17 15:04 -0700
  Re: Multible Fits using the same fit function lead to ?false? results. Christoph Bersch <usenet@bersch.net> - 2011-05-18 09:54 +0200
  Re: Multible Fits using the same fit function lead to ?false? results. Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2011-05-19 01:56 +0200

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