parameters: (N)
return_statement: return z, p, k
docstring: Return (z,p,k) for analog prototype of Nth-order Butterworth filter.
  
      The filter will have an angular (e.g. rad/s) cutoff frequency of 1.
  
      See Also
      --------
      butter : Filter design function using this prototype
docstring_summary: Return (z,p,k) for analog prototype of Nth-order Butterworth filter.
docstring_tokens: Return ( z p k ) for analog prototype of Nth - order Butterworth filter .
function: def buttap(N):
      """Return (z,p,k) for analog prototype of Nth-order Butterworth filter.
  
      The filter will have an angular (e.g. rad/s) cutoff frequency of 1.
  
      See Also
      --------
      butter : Filter design function using this prototype
  
      """
      if abs(int(N)) != N:
          raise ValueError("Filter order must be a nonnegative integer")
      z = numpy.array([])
      m = numpy.arange(-N+1, N, 2)
      # Middle value is 0 to ensure an exactly real pole
      p = -numpy.exp(1j * pi * m / (2 * N))
      k = 1
      return z, p, k
function_tokens: def buttap ( N ) : if abs ( int ( N ) ) != N : raise ValueError ( "Filter order must be a nonnegative integer" ) z = numpy . array ( [ ] ) m = numpy . arange ( - N + 1 , N , 2 ) # Middle value is 0 to ensure an exactly real pole p = - numpy . exp ( 1j * pi * m / ( 2 * N ) ) k = 1 return z , p , k