Direction field of a 2D first order ODE (original) (raw)

Scilab 5.3.3

Please note that the recommended version of Scilab is 2026.0.1. This page might be outdated.
See the recommended documentation of this function

Scilab help >> Graphics > 2d_plot > fchamp

fchamp

direction field of a 2D first order ODE

Calling Sequence

fchamp(f,t,xr,yr,[arfact,rect,strf]) fchamp(f,t,xr,yr,)

Arguments

f

An external (function or character string) or a list which describes the ODE.

-

It can be a function name f, wheref is supposed to be a function of typey=f(t,xy [p1,..pn]). f returns a column vector of size 2, y, which gives the value of the direction field f at pointxy=[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) andPi gives the value of the parameterpi.

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