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<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<!DOCTYPE MAN SYSTEM "../../manrev.dtd">
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<LANGUAGE>eng</LANGUAGE>
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<TITLE>portrait</TITLE>
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<TYPE>Scilab Function</TYPE>
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<DATE>April 1993</DATE>
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<SHORT_DESCRIPTION name="portrait"> 2 dimensional phase portrait. </SHORT_DESCRIPTION>
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<CALLING_SEQUENCE_ITEM>[]=portrait(f,[odem,xdim,npts,pinit]) </CALLING_SEQUENCE_ITEM>
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<PARAM_NAME>f</PARAM_NAME>
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<SP>: 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'</SP>
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<PARAM_NAME>options</PARAM_NAME>
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<SP>: The other parameters are optional. If omitted they will be asked interactively</SP>
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<PARAM_NAME>odem</PARAM_NAME>
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<SP>: gives the integration method to use. The value "default" can be used, otherwise see ode for a complete set of possibilities</SP>
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<PARAM_NAME>npts</PARAM_NAME>
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<SP>: a vector of size (2,10) [number-of-points,step] gives the step
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for integration and the number of requested points. The solution
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will be calculated and drawn for
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time=0:step:(step*[number-of-points])</SP>
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<PARAM_NAME>xdim</PARAM_NAME>
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<SP>: [xmin,xmax,ymin,ymax,zmin,zmax] the boundaries of the graphic frame.</SP>
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<PARAM_NAME>pinit</PARAM_NAME>
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<SP>: initial values for integration. A set of initial points can be given in a matrix</SP>
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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
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of a dynamical system dx/dt=f(t,x,[u]) (where u is an optional parameter )</P>
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deff('[ydot]=l_s(t,y)','ydot=a*y')