vertical lines



Michel Gosse escribi?:
> Hello
>
> The command :
> plot2d([x+1], [x,1,100], [gnuplot_preamble, "set logscale x; set grid;"],
> [nticks,1])$
> is supposed to plot vertical lines on xaxis. It is not the case. Why ?
> http://bmil.free.fr/plot.jpg
>
> Best regards
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> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>
>   
gnuplot selects where to plot the grid lines according to some internal 
rules. It seems it likes simple labels; in this case, powers of ten. Try 
to make the domain larger and you'll see what I mean:

load(draw)$
draw2d(explicit(x+1,x,1,100000), logx=true, grid=true);

I have seen a similar behavior with contours.

There is a workaround for this. If you download current cvs-draw 
package, you can force where to allocate grid lines:

draw2d(
  explicit(x+1,x,1,100),
  logx=true,
  grid=true,
  xtics={3,5,10,50,70,100});


Hope it helps

-- 
Mario Rodriguez Riotorto
www.biomates.net