function [x_p,y_p,y_new,error] = ppp_int_obs (x,y,U,A,B,C,D,A_u,delta,L)
## usage: x_new = ppp_int_obs (x,y,U,A,B,C,D,A_u,delta,L)
##
## Intermittent observer for PPP
##
## x,y Current estimated state and measured output
## U PPP control weights
## A,B,C,D System matrices
## A_u PPP basis matrix
## delta time step
## L Observer gain
## x_p, y_p predicted estimated state and output
## y_new corrected estimated current output
## error corresponding error
## Copyright (C) 2003 by Peter J. Gawthrop
## Sanity check
[n_x,n_u,n_y] = abcddim(A,B,C,D);
if nargin<10
L = zeros(n_x,n_y);
endif
## Corrector (on current value of output)
error = (C*x-y);
x_new = x - L*error;
y_new = C*x_new;
## Predictor (predicts Delta_OL ahead)
[y_p,us,x_p] = ppp_ystar (A,B,C,D,x_new,A_u,U,delta);
endfunction