contour2d — level curves of a surface on a 2D plot
contour2d(x,y,z,nz,[style,strf,leg,rect,nax]) contour2d(x,y,z,nz,<opt_args>)
two real row vectors of size n1 and n2: the grid.
real matrix of size (n1,n2), the values of the function on the
grid or a Scilab function which defines the surface z=f(x,y).
the level values or the number of levels.
If nz is an integer, its value gives the
number of level curves equally spaced from zmin to zmax as
follows:
z= zmin + (1:nz)*(zmax-zmin)/(nz+1)
Note that the zmin and zmax
levels are not drawn (generically they are reduced to points)
but they can be added with
[im,jm] = find(z == zmin); // or zmax plot2d(x(im)',y(jm)',-9,"000")
If nz is a vector, nz(i) gives
the value of the ith level curve.
This represents a sequence of statements
key1=value1,key2=value2,... where key1,
key2,... can be one of the following: style, leg, rect,
nax, strf or axesflag and frameflag (see plot2d)
see plot2d. The argument style gives
the dash styles or colors which are to be used for level curves. It
must have the same size as the number of levels.
contour2d draws level curves of a surface
z=f(x,y) on a 2D plot. The values of f(x,y) are
given by the matrix z at the grid points defined by
x and y.
You can change the format of the floating point number printed on the
levels by using xset("fpf",string) where string
gives the format in C format syntax (for example
string="%.3f"). Use string="" to switch back to
default format and Use string=" " to suppress printing. This
last feature is useful in conjunction with legends to display
the level numbers in a legend and not directly onto the level curves as
usual (see Examples).
The optional arguments style,strf,leg,rect,nax, can be
passed by a sequence of statements key1=value1, key2=value2,
... where keys may be
style,strf,leg,rect,nax.
In this case, the order has no special meaning.
Use contour to draw levels curves on a 3D surface.
contour2d(1:10,1:10,rand(10,10),5,rect=[0,0,11,11])
// changing the format of the printing of the levels
xset("fpf","%.2f")
clf()
contour2d(1:10,1:10,rand(10,10),5,rect=[0,0,11,11])
// now an example with level numbers drawn in a legend
// Caution there are a number of tricks...
x = linspace(0,4*%pi,80);
z = cos(x')*cos(x);
clf(); f=gcf();
xset("fpf"," ") // trick 1: this implies that the level numbers are not
// drawn on the level curves
f.color_map=jetcolormap(7);
// trick 2: to be able to put the legend on the right without
// interfering with the level curves use rect with a xmax
// value large enough
contour2d(x,x,z,-0.75:0.25:0.75,frameflag=3,rect=[0,0,5*%pi,4*%pi])
// trick 3: use legends (note that the more practical legend function
// will not work as soon as one of the level is formed by 2 curves)
legends(string(-0.75:0.25:0.75),1:7,"lr");
xtitle("Some level curves of the function cos(x)cos(y)")