This function returns a fir filter with an order and  cut-off specified.
  Also can be configured the types of filter as: low pass, high pass, band pass  
  and band stop. The filter also can be weighted by a window. Finally exist
  a parameter that indicates if should be plotted the time and frequency  
  impulse response.
  
  After starting the main routine just type the following command at the
  prompt:

  % By default it is low-pass, hamming window and not display the impulse response.
          h=get_fir_filter(ORDER,Wn);
  [h FTYPE]=get_fir_filter(ORDER,Wn);

  % By default it uses hamming window and not display the impulse response.
          h=get_fir_filter(ORDER,Wn,CTYPE);
  [h FTYPE]=get_fir_filter(ORDER,Wn,CTYPE);

  % By default it don't display the impulse response.
          h=get_fir_filter(ORDER,Wn,CTYPE,WINDOW);
  [h FTYPE]=get_fir_filter(ORDER,Wn,CTYPE,WINDOW);

  % All parameters are configured.
          h=get_fir_filter(ORDER,Wn,CTYPE,WINDOW,GRAPHON);
  [h FTYPE]=get_fir_filter(ORDER,Wn,CTYPE,WINDOW,GRAPHON);


  %% Low pass filter of order ORDER=20, cut-off at frequency to a*Fs/2, Hanning
  %% windows
  h=get_fir_filter(20,a,'low');

  %% High pass filter of order ORDER=20, cut-off at frequency a*Fs/2, Hanning
  %% windows
  h=get_fir_filter(20,a,'high');

  %% Band pass filter of order ORDER=40, cut-off at frequencies at 
  %% [a1*Fs/2 a2*Fs/2], Hanning windows
  h=get_fir_filter(40,[a1 a2],'bandpass');

  %% Reject pass filter of order ORDER=40, cut-off at frequencies at [a1*Fs/2 a2*Fs/2], 
  %% Hanning windows
  h=get_fir_filter(40,[a1 a2],'stop');

  
  Input:
  ORDER     is the a variable that content the order of filter, the length of 
            filter will be equal to ORDER+1.
  Wn        is a scalar variable or vector(1x2) that content the cut-off 
            frequencies.
  CTYPE     [optional] it is the cut-off type of the fir filter, it can be ser
            'low', 'high', 'bandpass' or 'stop'. By default this value is 'low'.
  WINDOW    [optional] it is a vector that represent the weighted values of the
            the filter.
  GRAPHON   [optional] enable or disable the display of the frequency  
            impulse response.

  Output:
  h         it is a vector of length ORDER+1 that represent a fir filter of
            order ORDER.
  FTYPE     [optional] returns the type of the fir filter.
            http://www.mathworks.com/help/signal/ug/fir-filter-design.html

  For help, bug reports and feature suggestions, please visit:
  http://www.nongnu.org/bsltl

Package: bsltl