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<div class="moz-cite-prefix">Hi Samuel and Scilabers<br>
<br>
My problem with freq and repfreq is that they require a "sys"
input, which implies I need to describe a response function of
some sort. For example (from the Scilab web-help):<br>
<br>
<a class="moz-txt-link-freetext" href="https://help.scilab.org/docs/6.0.1/en_US/freq.html">https://help.scilab.org/docs/6.0.1/en_US/freq.html</a> (example code)<br>
<pre class="scilabcode" style="margin-bottom: 0px; margin-top: 0px; overflow-x: auto; width: 728.094px; word-wrap: break-word; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">s</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">=</span><a class="scilabcommand" href="https://help.scilab.org/docs/6.0.1/en_US/poly.html" style="color: rgb(50, 185, 185); text-decoration: underline; font-style: normal;">poly</a><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">0</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">'</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">s</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">'</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">;</span>
<span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">=</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">s</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">+</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">1</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">/</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">s</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">^</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">3</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">-</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">5</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">*</span><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">s</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">+</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">4</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)</span>
<span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">rep</span><span class="scilaboperator" style="font-style: normal; color: rgb(92, 92, 92);">=</span><span class="scilabcommand" style="font-style: normal; color: rgb(50, 185, 185);">freq</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">"</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">num</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">"</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabid" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">(</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">"</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">den</span><span class="scilabstring" style="font-style: normal; color: rgb(188, 143, 143);">"</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">[</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">0</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">0.9</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">1.1</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">2</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">3</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">10</span><span class="scilabdefault" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="scilabnumber" style="font-style: normal; color: rgb(188, 143, 143);">20</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">]</span><span class="scilabopenclose" style="font-style: normal; color: rgb(74, 85, 219);">)
</span></pre>
<a class="moz-txt-link-freetext" href="https://help.scilab.org/docs/6.0.1/en_US/repfreq.html">https://help.scilab.org/docs/6.0.1/en_US/repfreq.html</a> (syntax)<br>
<pre style="margin-bottom: 0px; margin-top: 0px; overflow-x: auto; width: 819.115px; word-wrap: break-word; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">[ [</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,] </span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">repf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">]=</span><span class="functionid" style="font-weight: bold; color: rgb(0, 0, 0);">repfreq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">(</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">fmin</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">fmax</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);"> [,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">step</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">])</span>
<span class="default" style="font-style: normal; color: rgb(0, 0, 0);">[ [</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,] </span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">repf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">]=</span><span class="functionid" style="font-weight: bold; color: rgb(0, 0, 0);">repfreq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">(</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);"> [,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">])</span>
<span class="default" style="font-style: normal; color: rgb(0, 0, 0);">[ </span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">repf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">splitf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">]=</span><span class="functionid" style="font-weight: bold; color: rgb(0, 0, 0);">repfreq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">(</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">fmin</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">fmax</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);"> [,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">step</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">])</span>
<span class="default" style="font-style: normal; color: rgb(0, 0, 0);">[ </span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">repf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">splitf</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">]=</span><span class="functionid" style="font-weight: bold; color: rgb(0, 0, 0);">repfreq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">(</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">sys</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);"> [,</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">frq</span><span class="default" style="font-style: normal; color: rgb(0, 0, 0);">])</span></pre>
<br>
... So, the thing with the matlab freqz (as the example repeated
below shows) is just a basic FFT with sampling, etc:<br>
<br>
<span style="color:rgb(0,0,0);">h</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(50,185,185);">rand</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(188,143,143);">1</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(188,143,143);">64</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">;</span> <span
style="color:rgb(100,174,100);font-style:italic;">// impulse
response</span> (Matlab source code)<br>
<span style="color:rgb(0,0,0);">fs</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(188,143,143);">1000</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(0,0,0);">Nfft</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(188,143,143);">128</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(74,85,219);">[</span><span
style="color:rgb(0,0,0);">H</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">F</span><span
style="color:rgb(74,85,219);">]</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(0,0,0);">freqz</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">h</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(188,143,143);">1</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">Nfft</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">fs</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(0,0,0);">semilogx</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">F</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">mag2db</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(50,185,185);">abs</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">H</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">; </span><span
style="color:rgb(0,0,0);">grid</span> <span
style="color:rgb(0,0,0);">on</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(0,0,0);">xlabel</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(188,143,143);">'</span><span
style="color:rgb(188,143,143);">Frequency (Hz)</span><span
style="color:rgb(188,143,143);">'</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">; </span><span
style="color:rgb(0,0,0);">ylabel</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(188,143,143);">'</span><span
style="color:rgb(188,143,143);">Magnitude (dB)</span><span
style="color:rgb(188,143,143);">'</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">;</span><br>
<br>
It may very well be that I just don't understand the help page of
repfreq. For example it says about sys: "A siso or simo linear
dynamical system, in state space, transfer function or zpk
representations, in continuous or discrete time." - al right then,
it seems pretty capable, but so, what's "zpk" for example? ... my
apologies for finding the Scilab help to be cryptic and the
examples insufficient for me to solve my problem, hence I ask if
someone can take above matlab code and make it work in Scilab.<br>
<br>
Best regards,<br>
Claus<br>
<br>
On 15.09.2018 00:32, Samuel Gougeon wrote:<br>
</div>
<blockquote type="cite"
cite="mid:49e1b4a0-0f9c-d08b-194a-bbe166d729da@free.fr">
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http-equiv="Content-Type">
<div class="moz-cite-prefix">Le 14/09/2018 à 20:57, Claus Futtrup
a écrit :<br>
</div>
<blockquote
cite="mid:49ebf3dc-f34a-7664-f9ca-47beb7daa7a4@gmail.com"
type="cite">
<meta http-equiv="content-type" content="text/html;
charset=windows-1252">
<p>Dear Scilabers</p>
<p>I have calculated an impulse response and wish to do an FFT
to achieve the frequency response. I know what to expect. In
the matlab forum someone asked the same question and was
recommended to use freqz ... I wonder what would be the
equivalent function in Scilab?</p>
<span style="color:rgb(0,0,0);">https</span><span
style="color:rgb(255,170,0);">:</span><span
style="color:rgb(100,174,100);font-style:italic;">//www.mathworks.com/matlabcentral/answers/350350-how-to-plot-loudspeaker-frequency-response-from-its-impulse-response</span>
<p>For example, to replicate the code snippet (second answer in
above link), how to do this in Scilab?</p>
<span style="color:rgb(0,0,0);">h</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(50,185,185);">rand</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(188,143,143);">1</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(188,143,143);">64</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">;</span> <span
style="color:rgb(100,174,100);font-style:italic;">// impulse
response</span> (Matlab source code)<br>
<span style="color:rgb(0,0,0);">fs</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(188,143,143);">1000</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(0,0,0);">Nfft</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(188,143,143);">128</span><span
style="color:rgb(0,0,0);">;</span><br>
<span style="color:rgb(74,85,219);">[</span><span
style="color:rgb(0,0,0);">H</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">F</span><span
style="color:rgb(74,85,219);">]</span> <span
style="color:rgb(92,92,92);">=</span> <span
style="color:rgb(0,0,0);">freqz</span><span
style="color:rgb(74,85,219);">(</span><span
style="color:rgb(0,0,0);">h</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(188,143,143);">1</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">Nfft</span><span
style="color:rgb(0,0,0);">,</span><span
style="color:rgb(0,0,0);">fs</span><span
style="color:rgb(74,85,219);">)</span><span
style="color:rgb(0,0,0);">;</span><br>
</blockquote>
<br>
Did you have a look around freq() or repfreq()?<br>
<br>
We have somewhat the equivalence <span class="fontstyle0">invfreqz(H,F,m,n,W)
<=> </span><span class="fontstyle0">frfit(F*2*%pi, H, n,
W) // Scilab<br>
<br>
So you may look for the reciprocal of Scilab's frfit()</span>
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HTH<br>
Samuel<br>
<br>
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