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See the recommended documentation of this function

Scilab help >> Graphics > 2d_plot > contour2di

contour2di

compute level curves of a surface on a 2D plot

Calling Sequence

`[xc,yc]=contour2di(x,y,z,nz)`

Arguments

x,y

two real row vectors of size n1 and n2: the grid.

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.

xc,yc

vectors of identical sizes containing the contours definitions. See below for details.

Description

`contour2di` computes 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`.

`xc(1)` contains the level associated with first contour path, `yc(1)` contains the number `N1` of points defining this contour path and (`xc(1+(1:N1))`, `yc(1+(1:N1))` ) contain the coordinates of the paths points. The second path begin at `xc(2+N1)` and `yc(2+N1)` and so on.

Examples

```[xc,yc]=contour2di(1:10,1:10,rand(10,10),5);
k=1;n=yc(k);c=1;
while k+yc(k)<size(xc,'*')
n=yc(k);
plot2d(xc(k+(1:n)),yc(k+(1:n)),c)
c=c+1;
k=k+n+1;
end```

• contour — level curves on a 3D surface
• fcontour — level curves on a 3D surface defined by a function
• fcontour2d — level curves of a surface defined by a function on a 2D plot
• contour2d — level curves of a surface on a 2D plot
• plot2d — 2D plot
• xset — set values of the graphics context. This function is obsolete.

J.Ph.C.