# champ1

2D vector field plot with colored arrows

## Calling Sequence

    champ1(x, y, fx, fy, [arfact, rect, strf])

## Arguments

x, y

  two vectors which define the grid.

fx

  a matrix which describes the x component of the vector field. `fx(i,j)` is the x component of the vector field at point `(x(i),y(j))`.

fy

  a matrix which describes the y component of the vector field. `fy(i,j)` is the y component of the vector field at point `(x(i),y(j))`.

arfact

  an optional argument of type `real` which gives a scale factor for the display of the arrow heads on the plot (default value is 1.0).

rect

  a vector `rect = [xmin, ymin, xmax, ymax]` which gives the boundaries of the graphics frame to use.

frameflag

  controls the computation of the actual coordinate ranges from the minimal requested values. The associated value should be an integer ranging from 0 to 8.

axesflag

  specifies how the axes are drawn. The associated value should be an integer ranging from 0 to 5.

strf

  a string of length 3 "xyz" which has the same meaning as the `strf` parameter of `plot2d`. The first character `x` has no effect with `champ1`.

## Description

`champ1` draws a 2D vector field with colored arrows. The color of the arrows depends on the intensity of the field.

If you want arrows proportional to the intensity of the field, use `champ`.

Enter the command `champ1()` to see a demo.

Be cautioned about the fact that using meshgrid function before using `champ1` requires adjustment. For more details, see the last example below.

## Examples

    champ1(-5:5,-5:5,rand(11,11),rand(11,11),rect=[-10,-10,10,10],arfact=2)

champ1(-5:5,-5:5,rand(11,11),rand(11,11),rect=[-10,-10,10,10],arfact=2)

    // using meshgrid to get fx and fy
    clf()
    x = linspace(-1,1,30);
    y = linspace(-1,1,30);
    [X,Y] = meshgrid(x,y);
    fy = 2.*Y;
    fx = 2.*X;
    champ1(x,y,fx',fy'); //here we have transposed fx and fy

x = linspace(-1,1,30); y = linspace(-1,1,30); [X,Y] = meshgrid(x,y); fy = 2.*Y; fx = 2.*X; champ1(x,y,fx',fy'); //here we have transposed fx and fy

## See Also

- champ
- fchamp
- plot2d