Re: [Gnuplot-info] explanation to a short script

[Thomas S. <t.s...@fz...>]

strictly  speaking, nunzio's script only works if the smallest number is in
the
1st data line.

an example:

#ts.dat:
1 10
2 9
3 8
4 7
5 6
6 5
7 4
8 3
9 2
10 1

#script:
min=10**10
grab(x)=x<min?min=x:min=min
plot 'ts.dat' using 1:($2/grab($2))

gives a horizontal line and a warning about the empty y-range.
this means that gnuplot behaves like other programming languages
and there is no magic behind it.

a 2nd plot gives the correct result, as you have pointed out,
because then 'min' already contains the smallest value.

#script:
min=10**10
grab(x)=x<min?min=x:min=min
plot "ts.dat" using 1:($2/grab($2)), "" using 1:($2/grab($2))

... , "" using 1:($2/grab($2))
is equivalent to
... , "" using 1:($2/min)


bsmile wrote:
> 
> Dear Thomas,
> 
> Nunzio Losacco wrote a short script to get each number divided by the
> smallest number in a specific column, as
> min=10**10
> grab(x)=x<min?min=x:min=min
> plot 'disy.100' u 1:($3/grab($3))
> 
> I don't quite understand the logic behind although I checked that it works
> fine. If I were to do this, I would write something like
> 
> set term dumb
> min=10**10
> plot 'disy.100' u ($3<min?min=$3:min=min,$1):3
> 
> set term x11
> plot 'disy.100' u 1:($3/min)
> 
> and you easily see the idea I wrote it this way. I think this reflects a
> big
> problem for me to understand deeply how gnuplot deals with datafile and
> how
> it plots, which is obviously different from the standard programming
> languages. Thanks for your in-depth explanation or references,
> 
> Sincerely,
> Jon
> ------------------------------------------------------------------------------
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> 

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