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contour Scilab Group Scilab Function contour
NAME
contour - level curves on a 3D surface
CALLING SEQUENCE
contour(x,y,z,nz,[theta,alpha,leg,flag,ebox,zlev])
contour(x,y,z,nz,<opt_args>)
PARAMETERS
x,y : two real row vectors of size n1 and n2.
z : real matrix of size (n1,n2), the values of the function.
nz : 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. Note that it can be useful in order to see zmin and
zmax level curves to add an epsilon tolerance: nz=[
zmin+%eps,..,zmax-%eps].
<opt_args>
: a sequence of statements key1=value1, key2=value2, ... where keys may
be theta,alpha,leg, flag, ebox,zlev (see below). In this case, the
order has no special meaning.
theta, alpha
: real values giving in degree the spherical coordinates of the
observation point.
leg : string defining the captions for each axis with @ as a field
separator, for example "X@Y@Z".
flag : a real vector of size three flag=[mode,type,box].
mode : string (treatment of hidden parts).
mode>0
the hidden parts of the surface are removed and the surface is
painted with color mode.
mode=0
the hidden parts of the surface are drawn.
mode<0
only the shadow of the surface is painted with color or
pattern id -mode. Use xset() to see the meaning of the
ids.
type : an integer (scaling).
type=0 the plot is made using the current 3D scaling (set by
a previous call to param3d, plot3d, contour or
plot3d1).
type=1 rescales automatically 3d boxes with extreme aspect
ratios, the boundaries are specified by the value of
the optional argument ebox.
type=2 rescales automatically 3d boxes with extreme aspect
ratios, the boundaries are computed using the given
data.
type=3 3d isometric with box bounds given by optional ebox,
similarily to type=1
type=4 3d isometric bounds derived from the data, to
similarilytype=2
type=5 3d expanded isometric bounds with box bounds given
by optional ebox, similarily to type=1
type=6 3d expanded isometric bounds derived from the data,
similarily to type=2
box : an integer (frame around the plot).
box=0
nothing is drawn around the plot.
box=1
unimplemented (like box=0).
box=2
only the axes behind the surface are drawn.
box=3
a box surrounding the surface is drawn and captions are added.
box=4
a box surrounding the surface is drawn, captions and axes are
added.
ebox : used when type in flag is 1. It specifies the boundaries of the
plot as the vector [xmin,xmax,ymin,ymax,zmin,zmax].
zlev : real number.
DESCRIPTION
contour draws level curves of a surface z=f(x,y). The level curves are
drawn on a 3D surface. The optional arguments are the same as for the
function plot3d (except zlev) and their meanings are the same. They
control the drawing of level curves on a 3D plot. Only flag(1)=mode has a
special meaning.
mode=0 : the level curves are drawn on the surface defined by (x,y,z).
mode=1 : the level curves are drawn on a 3D plot and on the plan
defined by the equation z=zlev.
mode=2 : the level curves are drawn on a 2D plot.
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.
Usually we use contour2d to draw levels curves on a 2D plot. Enter the
command contour() to see a demo.
EXAMPLE
t=%pi*[-10:10]/10;
deff("[z]=surf(x,y)","z=sin(x)*cos(y)"); z=feval(t,t,surf);
rect=[-%pi,%pi,-%pi,%pi,-1,1];
contour(t,t,z,10,35,45," ",[0,1,0],rect)
// changing the format of the printing of the levels
xset("fpf","%.2f")
xbasc()
contour(t,t,z,10,flag=[0,1,0],ebox=rect)
SEE ALSO
contour2d, fcontour, fcontour2d, plot3d, xset
AUTHOR
J.Ph.C.
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