how to do contour plot using log scales



On Tue, 29 Oct 2013 15:14:10 +0000
- <mleoking at gmail.com> wrote:

> load(draw)$
> 
> draw3d(logx=true, logy=true, explicit(20*exp(-x^2-y^2)-10,x,0,2,y,-3,3),
> contour_levels = 15, contour = map, surface_hide = true)$
> 

Avoid zero and negative values before using logarithmic scales:

contour_plot (u^3 + v^2, [u, 1, 4], [v, 1, 4], [gnuplot_preamble, "set
cntrparam levels 12"], [logx], [logy])$

draw3d(logx=true, logy=true, explicit(20*exp(-x^2-y^2)-10,x,0.1,2,y,0.1,2),
contour_levels = 15, contour = map, surface_hide = true)$

--
Mario