function [fa,ifaila,icounta]=pidlsq(xa)
% PIDLSQ can accept multiple input vectors and return a matrix of outputs.
%
%
[nr,nc]=size(xa);
fa=[];
ifaila=zeros(nc,1);
fcounta=zeros(nc,1);
for i=1:nc
    [fap,ifaila(i),icounta(i)]=serial_pidlsq(xa(:,i));
    fa=[fa, fap];
end

function [f,ifail,icount]=serial_pidlsq(x)
%
% Parameter ID example formulated as nonlinear least squares problem.
%
%
global pid_data time_pts pid_parms pid_y0 pid_tol;
ifail=0; icount=1;
%
% Call the integrator only if x is physically reasonable, ie if
% x(1) and x(2) are nonnegative. Otherwise, report a failure.
%
if min(x) < 0
   ifail=1; icount=0; f=NaN;
   disp(' failure in pidobj')
else
   pid_parms=x;
   tol=pid_tol; options=odeset('RelTol',tol,'AbsTol',tol,'Jconstant',1);
   y0=pid_y0;
   [t,y]=ode15s(@yfunsp, time_pts, y0, options);
   r=y(:,1)-pid_data(:,1);
%   f=r'*r/2;
   f=r;
end

function yp=yfunsp(t,y)
%
% simple harmonic oscillator for parameter id example
%
% system form of y'' + c y' + k y = 0
%
global pid_parms;
yp=zeros(2,1);
yp(1)=y(2);
c=pid_parms(1);
k=pid_parms(2);
yp(2)= - k* y(1) - c*y(2);