samer@34: function x=expsin(n,k,l,phi)
samer@34: % expsin - return real part of complex exponential.
samer@34: %
samer@34: % expsin :: 
samer@34: %    N:natural ~'length of signal to return',
samer@34: %    real      ~'normalised frequency 1=sample rate',
samer@34: %    real      ~'decay rate, 1/time constant'
samer@34: % -> [[N]].
samer@34: %
samer@34: % expsin :: 
samer@34: %    N:natural ~'length of signal to return',
samer@34: %    real      ~'normalised frequency 1=sample rate',
samer@34: %    real      ~'decay rate, 1/time constant'
samer@34: %    real      ~'initial phase'
samer@34: % -> [[N]].
samer@34: % 
samer@34: % If initial phase not given, defaults to -pi/2 (so initial
samer@34: % value is zero with +ve slope).
samer@34: 
samer@34: if nargin<4, phi=pi/2; end
samer@34: t=0:n-1;
samer@34: x=real(exp((2*pi*k*i-l)*t-phi*i));