Sfgrayplot

smooth 2D plot of a surface defined by a function using colors

Calling Sequence

Sfgrayplot(x,y,f,<opt_args>)
Sfgrayplot(x,y,f [,strf, rect, nax, zminmax, colminmax, mesh, colout])

Arguments

x,y: real row vectors of size n1 and n2.
f: scilab function (z=f(x,y))
<opt_args>: This represents a sequence of statements key1=value1, key2=value2,... where key1, key2,... can be one of the following: strf, rect, nax, zminmax, colminmax, mesh, colout (see plot2d for the 3 first and fec for the 4 last).
strf,rect,nax: see plot2d.
zminmax, colminmax, mesh, colout: see fec.

Description

Sfgrayplot is the same as fgrayplot but the plot is smoothed. The function fec is used for smoothing. The surface is plotted assuming that it is linear on a set of triangles built from the grid (here with n1=5, n2=3):

_____________
| /| /| /| /|
|/_|/_|/_|/_| 
| /| /| /| /| 
|/_|/_|/_|/_|

The function colorbar may be used to see the color scale (but you must know (or compute) the min and max values).

Instead of Sfgrayplot, you can use Sgrayplot and this may be a little faster.

Enter the command Sfgrayplot() to see a demo.

Examples

// example #1: plot 4 surfaces
function z=surf1(x, y), z=x*y, endfunction
function z=surf2(x, y), z=x^2-y^2, endfunction
function z=surf3(x, y), z=x^3+y^2, endfunction
function z=surf4(x, y), z=x^2+y^2, endfunction
clf()
xset("colormap",[jetcolormap(64);hotcolormap(64)])
x = linspace(-1,1,60);
y = linspace(-1,1,60);
drawlater() ;
subplot(2,2,1)
  colorbar(-1,1,[1,64])
  Sfgrayplot(x,y,surf1,strf="041",colminmax=[1,64])
  xtitle("f(x,y) = x*y")
subplot(2,2,2)
  colorbar(-1,1,[65,128])
  Sfgrayplot(x,y,surf2,strf="041",colminmax=[65,128])
  xtitle("f(x,y) = x^2-y^2")
subplot(2,2,3)
  colorbar(-1,2,[65,128])
  Sfgrayplot(x,y,surf3,strf="041",colminmax=[65,128])
  xtitle("f(x,y) = x^3+y^2")
subplot(2,2,4)
  colorbar(0,2,[1,64])
  Sfgrayplot(x,y,surf4,strf="041",colminmax=[1,64])
  xtitle("f(x,y) = x^2+y^2")
drawnow() ;
show_window()

// example #2: plot surf3 and add some contour lines 
function z=surf3(x, y), z=x^3+y^2, endfunction
clf()
x = linspace(-1,1,60);
y = linspace(-1,1,60);
xset("colormap",hotcolormap(128))
drawlater() ;
colorbar(-1,2)
Sfgrayplot(x,y,surf3,strf="041")
fcontour2d(x,y,surf3,[-0.1, 0.025, 0.4],style=[1 1 1],strf="000")
xtitle("f(x,y) = x^3+y^2")
drawnow() ;
show_window()

// example #3: plot surf3 and use zminmax and colout optional arguments
//             to restrict the plot for -0.5<= z <= 1
function z=surf3(x, y), z=x^3+y^2, endfunction
clf()
x = linspace(-1,1,60);
y = linspace(-1,1,60);
xset("colormap",jetcolormap(128))
drawlater() ;
zminmax = [-0.5 1]; colors=[32 96];
colorbar(zminmax(1),zminmax(2),colors)
Sfgrayplot(x, y, surf3, strf="041", zminmax=zminmax, colout=[0 0], colminmax=colors)
fcontour2d(x,y,surf3,[-0.5, 1],style=[1 1 1],strf="000")
xtitle("f(x,y) = x^3+y^2, with parts under z = -0.5 and upper z = 1 removed")
drawnow() ;
show_window()

Authors

J.Ph.C.

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Last updated:
Wed Jan 26 16:24:14 CET 2011