freqz                 package:signal                 R Documentation

_s-_p_l_a_n_e _f_r_e_q_u_e_n_c_y _r_e_s_p_o_n_s_e

_D_e_s_c_r_i_p_t_i_o_n:

     Compute the z-plane frequency response of an ARMA model or IIR
     filter.

_U_s_a_g_e:

     ## Default S3 method:
     freqz(filt = 1, a = 1, n = 512, region = NULL, Fs = 2 * pi, ...)

     ## S3 method for class 'Arma':
     freqz(filt, ...)

     ## S3 method for class 'Ma':
     freqz(filt, ...)

     ## S3 method for class 'freqz':
     print(x, ...)

     ## S3 method for class 'freqz':
     plot(x, ...)

     ## Default S3 method:
     freqz_plot(w, h, ...) 

     ## S3 method for class 'freqz':
     freqz_plot(w, ...) 

_A_r_g_u_m_e_n_t_s:

    filt: for the default case, the moving-average coefficients of an
          ARMA model or filter. Generically, 'filt' specifies an
          arbitrary model or filter operation.

       a: the autoregressive (recursive) coefficients of an ARMA
          filter. 

       n: number of points at which to evaluate the frequency response. 

  region: ''half'' (the default) to evaluate around the upper half of
          the unit circle or 'whole'' to evaluate around the entire
          unit circle. 

      Fs: sampling frequency in Hz. If not specified, the frequencies
          are in radians. 

       w: for the default case, the array of frequencies. Generically,
          'w' specifies an object from which to plot a frequency
          response. 

       h: a complex array of frequency responses at the given
          frequencies. 

       x: object to be plotted. 

     ...: for methods of 'freqz', arguments are passed to the default
          method. For 'freqz_plot', additional arguments are passed
          through to 'plot'. 

_D_e_t_a_i_l_s:

     For fastest computation, 'n' should factor into a small number of
     small primes.

     When results of 'freqz' are printed, 'freqz_plot' will be called
     to display frequency plots of magnitude and phase. As with
     'lattice' plots, automatic printing does not work inside loops and
     function calls, so explicit calls to 'print' or 'plot' are needed
     there.

_V_a_l_u_e:

     For 'freqz' list of class 'freqz' with items: 

      h : array of frequencies. 

      f : complex array of frequency responses at those frequencies.

_A_u_t_h_o_r(_s):

     Original Octave version by John W. Eaton. Conversion to R by Tom
     Short.

_R_e_f_e_r_e_n_c_e_s:

     Octave Forge <URL: http://octave.sf.net>

_S_e_e _A_l_s_o:

     'filter', 'Arma', 'freqs'

_E_x_a_m_p_l_e_s:

     b = c(1,0,-1)
     a = c(1,0,0,0,0.25)
     freqz(b, a)

