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