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- Graphics Library
Please note that the recommended version of Scilab is 2023.1.0. This page might be outdated.
See the recommended documentation of this function
level curves of a surface on a 2D plot
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
the level values or the number of levels.
nzis 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
zmaxlevels are not drawn (generically they are reduced to points) but they can be added with
nzis a vector,
nz(i)gives the value of the ith level curve.
This represents a sequence of statements
key2,...can be one of the following: style, leg, rect, nax, strf or axesflag and frameflag (see plot2d)
see plot2d. The argument
stylegives 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
given by the matrix
z at the grid points defined by
You can change the format of the floating point number printed on the
levels by using
gives the format in C format syntax (for example
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
... where keys may be
In this case, the order has no special meaning.
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)")
- contour — level curves on a 3D surface
- contour2di — compute level curves of a surface on a 2D plot
- plot2d — 2D plot
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