champ
=====

2D vector field plot



Calling Sequence
~~~~~~~~~~~~~~~~


::

    champ(x,y,fx,fy,[arfact,rect,strf])
    champ(x,y,fx,fy,<opt_args>)




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))`.
: :<opt_args> This represents a sequence of statements
  `key1=value1,key2=value2`,... where `key1`, `key2,...` can be one of
  the following: arfact, rect, strf (see below).
: :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.
: :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
  `champ`.
:



Description
~~~~~~~~~~~

`champ` draws a 2D vector field. The length of the arrows is
proportional to the intensity of the field.

If you want colored arrows with the color of the arrows depending on
the intensity of the field, use `champ1`.

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



Sample
~~~~~~



Examples
~~~~~~~~


::

    // using rect as plot boundaries 
    champ(-5:5,-5:5,`rand`_(11,11),`rand`_(11,11),rect=[-10,-10,10,10],arfact=2)
    // using (x,y) to get boundaries 
    `clf`_()
    champ(-5:5,-5:5,`rand`_(11,11),`rand`_(11,11),2,[-10,-10,10,10],"021")




See Also
~~~~~~~~


+ `champ1`_ 2D vector field plot with colored arrows
+ `fchamp`_ direction field of a 2D first order ODE
+ `plot2d`_ 2D plot


.. _fchamp: fchamp.html
.. _champ1: champ1.html
.. _plot2d: plot2d.html