function x = expsig(N,a)
%  expsig --> Exponential signal.
%
%  <Synopsis>
%    x = expsig(N,a)
%
%  <Description>
%    Generates an N-vector, which is the exponential signal a^n.
%    If the parameter a is real, then x(n) is a real signal. When
%    the parameter a is complex valued, it can be expressed as
%    a = r*exp(j*theta) where r and theta are now the parameters.
%
%  <See Also>
%    unitsig --> Unit sample, unit step, and unit ramp sequences.
%    sinsig  --> Sum of sinusoidal sequences.

%  <Revision>
%    Peter S.K. Hansen, IMM, Technical University of Denmark
%
%    Last revised: February 7, 2000
%-----------------------------------------------------------------------

% Check the required input arguments.
if (nargin < 2)
  error('Not enough input arguments.')
end

% Generate the sequence.
x = a.^(0:N-1).';

%-----------------------------------------------------------------------
% End of function expsig
%-----------------------------------------------------------------------