Scilab Function
Last update : 18/05/2014
fchamp - direction field of a 2D first order
ODE
Calling Sequence
- fchamp(f,t,xr,yr,[arfact,rect,strf])
- fchamp(f,t,xr,yr,<opt_args>)
Parameters
-
f: An external (function or character string) or a list which
describes the ODE.
-
-It can be a function name f, where
f is supposed to be a function of type
y=f(t,xy [p1,..pn]). f returns a
column vector of size 2, y, which gives the value
of the direction field f at point
xy=[x,y] and at time t.
-
-It can also be an object of type list,
list(f,P1,..Pn) where f is a
function of type y=f(t,xy,p1,..pn) and
Pi gives the value of the parameter
pi.
-
t: The selected time.
-
xr,yr: Two row vectors of size n1 and n2 which define the grid on
which the direction field is computed.
-
<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,rect,strf: Optional arguments, see champ.
Description
fchamp is used to draw the direction field of a 2D first
order ODE defined by the external function f. Note that if
the ODE is autonomous, argument t is useless, but it must be
given.
Enter the command fchamp() to see a demo.
Examples
deff("[xdot] = derpol(t,x)",..
["xd1 = x(2)";..
"xd2 = -x(1) + (1 - x(1)**2)*x(2)";..
"xdot = [ xd1 ; xd2 ]"])
xf= -1:0.1:1;
yf= -1:0.1:1;
fchamp(derpol,0,xf,yf)
clf()
fchamp(derpol,0,xf,yf,1,[-2,-2,2,2],"011")
See Also
champ, champ1,
Author
J.Ph.C.