fsfirlin
========

design of FIR, linear phase filters, frequency sampling technique



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


::

    [hst]=fsfirlin(hd,flag)




Arguments
~~~~~~~~~

:hd vector of desired frequency response samples
: :flag is equal to 1 or 2, according to the choice of type 1 or type
  2 design
: :hst vector giving the approximated continuous response on a dense
  grid of frequencies
:



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

function for the design of FIR, linear phase filters using the
frequency sampling technique



Examples
~~~~~~~~


::

    //
    //Example of how to use the fsfirlin macro for the design 
    //of an FIR filter by a frequency sampling technique.
    //
    //Two filters are designed : the first (response hst1) with 
    //abrupt transitions from 0 to 1 between passbands and stop 
    //bands; the second (response hst2) with one sample in each 
    //transition band (amplitude 0.5) for smoothing.
    //
    hd=[`zeros`_(1,15) `ones`_(1,10) `zeros`_(1,39)];//desired samples
    hst1=fsfirlin(hd,1);//filter with no sample in the transition
    hd(15)=.5;hd(26)=.5;//samples in the transition bands
    hst2=fsfirlin(hd,1);//corresponding filter
    pas=1/`prod`_(`size`_(hst1))*.5;
    fg=0:pas:.5;//normalized frequencies grid
    `plot2d`_([1 1].*.fg(1:257)',[hst1' hst2']);
    
    // 2nd example
    hd=[0*`ones`_(1,15) `ones`_(1,10) 0*`ones`_(1,39)];//desired samples
    hst1=fsfirlin(hd,1);//filter with no sample in the transition
    hd(15)=.5;hd(26)=.5;//samples in the transition bands
    hst2=fsfirlin(hd,1);//corresponding filter
    pas=1/`prod`_(`size`_(hst1))*.5;
    fg=0:pas:.5;//normalized frequencies grid
    n=`prod`_(`size`_(hst1))
    `plot`_(fg(1:n),hst1);
    `plot2d`_(fg(1:n)',hst2',[3],"000");




See Also
~~~~~~~~


+ `ffilt`_ coefficients of FIR low-pass
+ `wfir`_ linear-phase FIR filters


.. _ffilt: ffilt.html
.. _wfir: wfir.html