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portrait Scilab Group Scilab Function portrait
NAME
portrait - 2 dimensional phase portrait.
CALLING SEQUENCE
[]=portrait(f,[odem,xdim,npts,pinit])
PARAMETERS
f : a Scilab external which gives the field of the dynamical system.
Hence it can be a macro name which computes the field at time t and
point x [y]=f(t,x,[u]) or a list list(f1,u1) where f1 is a macro of
type [y]=f1(t,x,u) or a character string. The macro can be used to
simulate a continuous or discrete system and in case of discrete
system the second parameter must be set to 'discrete'
.I rest
: The other parameters are optional. If omitted they will be asked
interactively
odem : gives the integration method to use. The value "default" can
be used, otherwise see ode for a complete set of possibilities
npts : a vector of size (2,10) [number-of-points,step] gives the
step for integration and the number of requested points. The
solution will be calculated and drawn for
time=0:step:(step*[number-of-points])
xdim : [xmin,xmax,ymin,ymax,zmin,zmax] the boundaries of the graphic
frame.
pinit
: initial values for integration. A set of initial points can be
given in a matrix
pinit = [x0(1), x1(1),...., xn(1)
x0(2), x1(2),...., xn(2)
x0(3), x1(3),...., xn(3)].
DESCRIPTION
Interactive integration and display of a 2 dimensional phase portrait of
a dynamical system dx/dt=f(t,x,[u]) (where u is an optional parameter )
EXAMPLE
a=rand(2,2)
deff('[ydot]=l_s(t,y)','ydot=a*y')
portrait(l_s)
SEE ALSO
ode
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