Dimpulse Function in Matlab - matlab

Question

Im working with Signals and i need to determine the impulse of a Discrete Signal using Matlab dimpulse function.
For some reason i dont have dimpulse function on my Matlab...
Does anyone knows if its really an Matlab function or a custom made function? if its an Matlab one which toolbox is it?
i tried the commands which dimpulse and it says it doesn't find it....I need this function for Discret Signals...
I´m running Matlab 2012b on a Mac if that helps ...
Thanks ...

Answer 1

Dimpulse is not an official Matlab function. However, Google turned up a few universities that have written the function, such as here:
function [yout,x,n] = dimpulse(a,b,c,d,iu,n)
%DIMPULSE Impulse response of discrete-time linear systems.
% DIMPULSE(A,B,C,D,IU) plots the response of the discrete system:
%
% x[n+1] = Ax[n] + Bu[n]
% y[n] = Cx[n] + Du[n]
%
% to an unit sample applied to the inputs IU. The number of
% points is determined automatically.
%
% DIMPULSE(NUM,DEN) plots the impulse response of the polynomial
% transfer function G(z) = NUM(z)/DEN(z) where NUM and DEN contain
% the polynomial coefficients in descending powers of z.
%
% DIMPULSE(A,B,C,D,IU,N) or DIMPULSE(NUM,DEN,N) uses the user-
% supplied number of points, N. When invoked with left hand
% arguments,
% [Y,X] = DIMPULSE(A,B,C,D,...)
% [Y,X] = DIMPULSE(NUM,DEN,...)
% returns the output and state time history in the matrices Y and X.
% No plot is drawn on the screen. Y has as many columns as there
% are outputs and X has as many columns as there are states.
%
% See also IMPULSE, STEP, INITIAL, LSIM.
% J.N. Little 4-21-85
% Revised CMT 7-31-90, ACWG 5-30-91, AFP 10-1-94
% Copyright 1986-2002 The MathWorks, Inc.
% $Revision: 1.15 $ $Date: 2002/04/04 15:15:36 $
%warning(['This calling syntax for ' mfilename ...
% ' will not be supported in the future: use IMPULSE(SYS,...) instead.'])
ni = nargin;
no = nargout;
if ni==0,
eval('exresp(''dimpulse'')')
return
end
error(nargchk(2,6,ni))
Ts = -1;
% Determine which syntax is being used
switch ni
case 2
if size(a,1)>1,
% SIMO syntax
a = num2cell(a,2);
den = b;
b = cell(size(a,1),1);
b(:) = {den};
end
sys = tf(a,b,Ts);
n = [];
case 3
% Transfer function form with time vector
if size(a,1)>1,
% SIMO syntax
a = num2cell(a,2);
den = b;
b = cell(size(a,1),1);
b(:) = {den};
end
sys = tf(a,b,Ts);
n = c;
case 4
% State space system without iu or time vector
sys = ss(a,b,c,d,Ts);
n = [];
otherwise
% State space system, with iu but w/o time vector
if min(size(iu))>1,
error('IU must be a vector.');
elseif isempty(iu),
iu = 1:size(d,2);
end
sys = ss(a,b(:,iu),c,d(:,iu),Ts);
if ni<6,
n = [];
end
end
if no==1,
yout = impulse(sys,n);
yout = yout(:,:);
elseif no>1,
[yout,t,x] = impulse(sys,n);
yout = yout(:,:);
x = x(:,:);
n = length(t);
else
impulse(sys,n)
end
% end dimpulse