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<?xml version="1.0" encoding="UTF-8"?>
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* Add some comments about XML file
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<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" version="5.0-subset Scilab" xml:lang="en_US" xml:id="damp">
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<refname>damp</refname>
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<refpurpose>Natural frequencies and damping factors. </refpurpose>
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<title>Calling Sequence</title>
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[wn,z] = damp(P [,dt])
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[wn,z] = damp(R [,dt])
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<title>Parameters</title>
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A linear dynamical system (see <link linkend="syslin">syslin</link>).
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An array of polynomials.
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An array of real or complex floating point numbers.
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A non negative scalar, with default value 0.
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vector of floating point numbers in increasing
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order: the natural pulsation in rd/s.
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vector of floating point numbers: the damping factors.
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<title>Description</title>
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The denominator second order continuous time transfer function
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with complex poles can be written as <literal>s^2+2*z*wn*s+wn^2</literal> where<literal>z</literal>
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is the damping factor and <literal>wn </literal>the natural pulsation.
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If <literal>sys</literal> is a continuous time system,
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<literal>[wn,z] = damp(sys)</literal> returns in <literal>wn</literal> the natural
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pulsation <latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the damping factors
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<latex>\xi</latex> of the poles of the linear dynamical system
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<literal>sys</literal>. The <literal>wn</literal> and
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<literal>z</literal> arrays are ordered according to the increasing
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If <literal>sys</literal> is a discrete time system
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<literal>[wn,z] = damp(sys)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the continuous time
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equivalent poles of <literal>sys</literal>. The
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<literal>wn</literal> and <literal>z</literal> arrays are
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ordered according to the increasing pulsation order.
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<literal>[wn,z] = damp(P)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the set of roots of the polynomials
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stored in the <literal>P</literal> array. If
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<literal>dt</literal> is given and non 0, the roots are first
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converted to their continuous time equivalents.
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The <literal>wn</literal> and <literal>z</literal> arrays are ordered
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according to the increasing pulsation order.
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<literal>[wn,z] = damp(R)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the set of roots stored in the
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<literal>R</literal> array.
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If <literal>dt</literal> is given and non 0, the roots are first
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converted to their continuous time equivalents.
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<literal>wn(i)</literal> and <literal>z(i)</literal> are the the
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natural pulsation and damping factor of <literal>R(i)</literal>.
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<title>Examples</title>
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<programlisting role="example"><![CDATA[
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<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org" version="5.0-subset Scilab" xml:lang="en_US" xml:id="damp">
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<refname>damp</refname>
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<refpurpose>Natural frequencies and damping factors. </refpurpose>
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<title>Calling Sequence</title>
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[wn,z] = damp(P [,dt])
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[wn,z] = damp(R [,dt])
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<title>Parameters</title>
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A linear dynamical system (see <link linkend="syslin">syslin</link>).
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An array of polynomials.
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An array of real or complex floating point numbers.
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A non negative scalar, with default value 0.
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vector of floating point numbers in increasing
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order: the natural pulsation in rd/s.
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vector of floating point numbers: the damping factors.
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<title>Description</title>
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The denominator second order continuous time transfer function
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with complex poles can be written as <literal>s^2+2*z*wn*s+wn^2</literal> where<literal>z</literal>
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is the damping factor and <literal>wn </literal>the natural pulsation.
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If <literal>sys</literal> is a continuous time system,
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<literal>[wn,z] = damp(sys)</literal> returns in <literal>wn</literal> the natural
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pulsation <latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the damping factors
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<latex>\xi</latex> of the poles of the linear dynamical system
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<literal>sys</literal>. The <literal>wn</literal> and
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<literal>z</literal> arrays are ordered according to the increasing
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If <literal>sys</literal> is a discrete time system
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<literal>[wn,z] = damp(sys)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the continuous time
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equivalent poles of <literal>sys</literal>. The
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<literal>wn</literal> and <literal>z</literal> arrays are
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ordered according to the increasing pulsation order.
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<literal>[wn,z] = damp(P)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the set of roots of the polynomials
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stored in the <literal>P</literal> array. If
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<literal>dt</literal> is given and non 0, the roots are first
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converted to their continuous time equivalents.
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The <literal>wn</literal> and <literal>z</literal> arrays are ordered
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according to the increasing pulsation order.
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<literal>[wn,z] = damp(R)</literal> returns in
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<literal>wn</literal> the natural pulsation
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<latex>\omega_n</latex>(in rd/s) and in <literal>z</literal> the
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damping factors <latex>\xi</latex> of the set of roots stored in the
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<literal>R</literal> array.
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If <literal>dt</literal> is given and non 0, the roots are first
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converted to their continuous time equivalents.
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<literal>wn(i)</literal> and <literal>z(i)</literal> are the the
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natural pulsation and damping factor of <literal>R(i)</literal>.
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<title>Examples</title>
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<programlisting role="example"><![CDATA[
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num=22801+4406.18*s+382.37*s^2+21.02*s^3+s^4;
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den=22952.25+4117.77*s+490.63*s^2+33.06*s^3+s^4
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h=syslin('c',num/den);
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]]></programlisting>
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The following example illustrates the effect of the damping factor on
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the frequency response of a second order system.
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<programlisting role="example"><![CDATA[
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The following example illustrates the effect of the damping factor on
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the frequency response of a second order system.
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<programlisting role="example"><![CDATA[
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legend('$\xi='+string(Z)+'$')
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plot(wn/(2*%pi)*[1 1],[0 70],'r') //natural pulsation
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]]></programlisting>
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It produces this plot:
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<imagedata fileref="../images/damp.svg"/>
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Computing the natural pulsations and daping ratio for a set of roots:
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<programlisting role="example"><![CDATA[
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Z=[0.95 0.7 0.5 0.3 0.13 0.0001];
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H=syslin('c',1+5*s+10*s^2,s^2+2*z*wn*s+wn^2);
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p=gce();p=p.children;
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title("$\frac{1+5 s+10 s^2}{\omega_n^2+2\omega_n\xi s+s^2}, \quad \omega_n=1$")
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legend('$\xi='+string(Z)+'$')
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plot(wn/(2*%pi)*[1 1],[0 70],'r') //natural pulsation
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Computing the natural pulsations and daping ratio for a set of roots:
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<programlisting role="example"><![CDATA[
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[wn,z] = damp((1:5)+%i)
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]]></programlisting>
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<title>See Also</title>
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<simplelist type="inline">
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<link linkend="spec">spec</link>
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<link linkend="roots">roots</link>
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<title>See Also</title>
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<simplelist type="inline">
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<link linkend="spec">spec</link>
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<link linkend="roots">roots</link>