mrfit
=====

frequency response fit



Calling Sequence
~~~~~~~~~~~~~~~~


::

    sys=mrfit(w,mag,order)
    [num,den]=mrfit(w,mag,order)
    sys=mrfit(w,mag,order,weight)
    [num,den]=mrfit(w,mag,order,weight)




Arguments
~~~~~~~~~

:w positive real vector of frequencies (Hz)
: :mag real vector of frequency responses magnitude (same size as `w`)
: :order integer (required order, degree of `den`)
: :weight positive real vector (default value `ones(w)`).
: :num,den stable polynomials
:



Description
~~~~~~~~~~~

`sys=mrfit(w,mag,order,weight)` returns a bi-stable transfer function
`G(s)=sys=num/den`, of of given `order` such that its frequency
response magnitude `abs(G(w(i)))` matches `mag(i)` i.e.
`abs(freq(num,den,%i*w))` should be close to `mag`. `weight(i)` is the
weigth given to `w(i)`.



Examples
~~~~~~~~


::

    w=0.01:0.01:2;s=`poly`_(0,'s');
    G=`syslin`_('c',2*(s^2+0.1*s+2),(s^2+s+1)*(s^2+0.3*s+1)); // syslin('c',Num,Den);
    fresp=`repfreq`_(G,w);
    mag=`abs`_(fresp);
    Gid=mrfit(w,mag,4);
    frespfit=`repfreq`_(Gid,w);
    `plot2d`_([w',w'],[mag(:),`abs`_(frespfit(:))])




See Also
~~~~~~~~


+ `cepstrum`_ cepstrum calculation
+ `frfit`_ frequency response fit
+ `freq`_ frequency response
+ `calfrq`_ frequency response discretization


.. _frfit: frfit.html
.. _freq: freq.html
.. _cepstrum: cepstrum.html
.. _calfrq: calfrq.html