Re: error "contradicting arguments"

[Ethan A M. <merritt@u.washington.edu>]

On Tuesday 30 December 2008, Ralf Juengling wrote:
> Greetings,
> 
> When I do this
> 
> set style line 1 lt -1 lw 2
> set style increment user
> plot 'data.txt' with lines ls 1 lc rgb variable
> 
> gnuplot gives me an error:
> 
>   line 3: duplicated or contradicting arguments in plot options
> 
> Not sure why it generates an error, the user-defined linestyle
> does not specify a color. 

From the perspective of the internal implementation, 
the line style does specify a color; the color is "lt -1".

But the real problem is that the command parser stops
looking for further style information once it sees "ls 1".
You will see this at the very top of the routine lp_parse()
in file misc.c

Given that you have already done "set style increment user",
the command "plot ... lt 1 lc rgb variable" should do the
same thing as "ls 1 lc rgb variable" would have done if the
parser accepted it.

> Bug or feature? 

Probably no one thought about it much one way or the other.
I don't know if there would be further problems if the parser were
changed to accept additional qualifiers after the "ls 1".
You could try modifying the code in lp_parse().

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742