Scilab Function

contour2d - level curves of a surface on a 2D plot

### Calling Sequence

  `contour2d(x,y,z,nz,[style,strf,leg,rect,nax])`
  `contour2d(x,y,z,nz,<opt_args>)`

### Parameters

- `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.

<opt_args> : 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)

- `style,strf,leg,rect,nax` : 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.

### Description

`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.

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.

Enter the command `contour2d()` to see a demo.

### Examples

    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")
    xbasc()
    contour2d(1:10,1:10,rand(10,10),5,rect=[0,0,11,11])

### See Also

`contour` `fcontour` `fcontour2d` `contour2di` `plot2d` `xset`

### Author

J.Ph.C.