gnuplot-info

[Gnuplot-info] depth in gnuplot?

[Luiz F. C C. <lf...@gm...>]

Hello, I'm new to the List and a new gnuplot user as well. I hope
you don't mind my asking this beginner's question. Here it goes:

I am trying to make a plot of the region in xy-plane bounded by the
curves x=-y^2, x-y=4, y=-1 and y=2. This is what I got so far:


set trange [-1:2]
set xrange [-5:7]
set yrange [-2:3]
unset key
set size 1,1
set origin 0,0
set multiplot
set size 1,1
set origin 0,0
plot 2 lt -1, -1 lt -1, sqrt(-x) lt -1, -sqrt(-x) lt -1, x-4 lt -1
set size 1,1
set origin 0,0
set parametric
plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2
unset multiplot
reset


It took me the whole afternoon to come up with this ;)

The problem is I can't see distinctly and completely the lines that
make up the boundary of the region. What be done? is there anything
such as depth as in xfig or is there an easier way to achieve this?
I will appreciate any help.

Thanks, 

Luiz Fernando

Re: [Gnuplot-info] depth in gnuplot?

[<br...@ph...>]

Luiz Fernando C Camargo wrote:

[...]
> set multiplot
> set size 1,1
> set origin 0,0
> plot 2 lt -1, -1 lt -1, sqrt(-x) lt -1, -sqrt(-x) lt -1, x-4 lt -1
> set size 1,1
> set origin 0,0
> set parametric
> plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2
> unset multiplot

Using multiplot like this is almost never a good idea.

> The problem is I can't see distinctly and completely the lines that
> make up the boundary of the region. What be done? 

Change the order of plotting.  Make all plots parametric, and do the
'filledcurves" ones *first*.  gnuplot draws all the functions and 
datasets you hand it in the given order, so what you draw later will 
overprint what was drawn earlier.

[Gnuplot-info] Re: depth in gnuplot?

[Luiz F. C C. <lf...@gm...>]

Hans-Bernhard Bröker wrote:

> Change the order of plotting.  Make all plots parametric, and do
> the 'filledcurves" ones *first*.  gnuplot draws all the functions
> and datasets you hand it in the given order, so what you draw
> later will overprint what was drawn earlier.


OK, problem is solved, thank you very much. Now please, take a look
at this modified code:

set xrange [-5:7]
set yrange [-2:3]
unset key
set parametric
set trange [-1:2]
set label "R" at -1, 1.5 front
set style line 1 lt -1 lw 1.5
plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2, \
     -((5*t-1)/3)**2, (5*t-1)/3 ls 1 with lines, \
     (5*t-1)/3+4, (5*t-1)/3 ls 1 with lines, \
     4*t-1, 2 ls 1 with lines, 4*t-1,-1 ls 1 with lines
set zeroaxis

I had to append the option 'front' to the 'set label' command for,
otherwise, the label would be underneath the colored region and
wouldn't be visible. Now, I don't have a similar option for the 'set
zeroaxis' command.  Only part of the xzeroaxis and of the yzeroaxis
are visible, what can I do in this case?

Thank you very much.

Luiz Fernando

Re: [Gnuplot-info] Re: depth in gnuplot?

[<br...@ph...>]

Luiz Fernando C Camargo wrote:

> set xrange [-5:7]
> set yrange [-2:3]
> unset key
> set parametric
> set trange [-1:2]
> set label "R" at -1, 1.5 front
> set style line 1 lt -1 lw 1.5
> plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2, \
>      -((5*t-1)/3)**2, (5*t-1)/3 ls 1 with lines, \
>      (5*t-1)/3+4, (5*t-1)/3 ls 1 with lines, \
>      4*t-1, 2 ls 1 with lines, 4*t-1,-1 ls 1 with lines
> set zeroaxis
> 
> I had to append the option 'front' to the 'set label' command for,
> otherwise, the label would be underneath the colored region and
> wouldn't be visible. Now, I don't have a similar option for the 'set
> zeroaxis' command.  Only part of the xzeroaxis and of the yzeroaxis
> are visible, what can I do in this case?

The same thing, really: fix the order of commands.  "set" commands in 
gnuplot are settings, not actions, i.e. they don't draw anything by 
themselves.  To be effective, they have to be given *before* the 'plot' 
command.

[Gnuplot-info] Re: Re: depth in gnuplot?

[Luiz F. C C. <lf...@gm...>]

Hans-Bernhard Bröker wrote:

> Luiz Fernando C Camargo wrote:
> 
>> set xrange [-5:7]
>> set yrange [-2:3]
>> unset key
>> set parametric
>> set trange [-1:2]
>> set label "R" at -1, 1.5 front
>> set style line 1 lt -1 lw 1.5
>> plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2, \
>>      -((5*t-1)/3)**2, (5*t-1)/3 ls 1 with lines, \
>>      (5*t-1)/3+4, (5*t-1)/3 ls 1 with lines, \
>>      4*t-1, 2 ls 1 with lines, 4*t-1,-1 ls 1 with lines
>> set zeroaxis
>> 
>> I had to append the option 'front' to the 'set label' command for,
>> otherwise, the label would be underneath the colored region and
>> wouldn't be visible. Now, I don't have a similar option for the 'set
>> zeroaxis' command.  Only part of the xzeroaxis and of the yzeroaxis
>> are visible, what can I do in this case?
> 
> The same thing, really: fix the order of commands.  "set" commands in
> gnuplot are settings, not actions, i.e. they don't draw anything by
> themselves.  To be effective, they have to be given *before* the 'plot'
> command.


All right, but... even if the 'set zeroaxis' command is given before
the 'plot' command, like this,

set xrange [-5:7]
set yrange [-2:3]
unset key
set parametric
set trange [-1:2]
set label "R" at -1, 1.5 front
set style line 1 lt -1 lw 1.5
set zeroaxis
plot -t**2, t lt 5 with filledcu y2, t+4, t lt -2 with filledcu y2, \
     -((5*t-1)/3)**2, (5*t-1)/3 ls 1 with lines, \
     (5*t-1)/3+4, (5*t-1)/3 ls 1 with lines, \
     4*t-1, 2 ls 1 with lines, 4*t-1,-1 ls 1 with lines

even then the axes are only partially visible...