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