lincos
function sys=lincos(scs_m,x0,u0,param)
// NAME
// lincos - Constructs by linearization a linear state-space
// model from a general dynamical system described by a
// scicos diagram
// CALLING SEQUENCE
//
// sys= lincos(scs_m [,x0,u0 [,param] ])
//
//
// PARAMETERS
//
// scs_m: a Scicos data structure
// x0: column vector. Continuous state around which linearization to be done (default 0)
// u0: column vector. Input around which linearization to be done (default 0)
// param: list with two elements (default list(1.d-6,0))
// param(1): scalar. Perturbation level for linearization; the following variation is used
// del([x;u])_i = param(1)+param(1)*1d-4*abs([x;u])_i
// param(2): scalar. Time t.
//
// sys: state-space system
//
// DESCRIPTION
// Constructs by linearization a linear state-space
// model from a general dynamical system described by a
// scicos diagram scs_m. Input and output ports, normally
// used inside superblocks, should be used to specify
// inputs and outputs in the scicos diagram. Suppose the
// scicos diagram to be linearized is called mysystem and
// it is saved in mysystem.cos in the current directory. The scicos
// diagram scs_m can be obtained either by
// scs_m = scicos('mysystem.cos');
// followed by a quit in the scicos menu, or by
// load('mysystem.cos')
// which creates by default a variable called scs_m.
[lhs,rhs]=argn(0)
IN=[];OUT=[];
//check version
current_version = get_scicos_version()
scicos_ver = find_scicos_version(scs_m)
//do version
if scicos_ver<>current_version then
ierr=execstr('scs_m=do_version(scs_m,scicos_ver)','errcatch')
if ierr<>0 then
error('Can''t convert old diagram (problem in version)')
return
end
end
for i=1:size(scs_m.objs)
if typeof(scs_m.objs(i))=='Block' then
if scs_m.objs(i).gui=='IN_f' then
scs_m.objs(i).gui='INPUTPORT';
IN=[IN scs_m.objs(i).model.ipar]
elseif scs_m.objs(i).gui=='OUT_f' then
scs_m.objs(i).gui='OUTPUTPORT';
OUT=[OUT scs_m.objs(i).model.ipar]
end
end
end
IN=-sort(-IN);
if or(IN<>[1:size(IN,'*')]) then
error('Input ports are not numbered properly.')
end
OUT=-sort(-OUT);
if or(OUT<>[1:size(OUT,'*')]) then
error('Output ports are not numbered properly.')
end
//load scicos lib
load('SCI/macros/scicos/lib')
//compile scs_m
[bllst,connectmat,clkconnect,cor,corinv,ok]=c_pass1(scs_m);
if ~ok then
error('Diagram does not compile in pass 1');
end
%cpr=c_pass2(bllst,connectmat,clkconnect,cor,corinv);
if %cpr==list() then
ok=%f,
end
if ~ok then
error('Diagram does not compile in pass 2');
end
sim=%cpr.sim;state=%cpr.state;
//
inplnk=sim.inplnk;inpptr=sim.inpptr;
outlnk=sim.outlnk;outptr=sim.outptr;ipptr=sim.ipptr;
ki=[];ko=[];nyptr=1;
for kfun=1:length(sim.funs)
if sim.funs(kfun)=='output' then
sim.funs(kfun)='bidon'
ko=[ko;[kfun,sim.ipar(ipptr(kfun))]];
elseif sim.funs(kfun)=='input' then
sim.funs(kfun)='bidon'
ki=[ki;[kfun,sim.ipar(ipptr(kfun))]];
end
end
[junk,ind]=sort(-ko(:,2));ko=ko(ind,1);
[junk,ind]=sort(-ki(:,2));ki=ki(ind,1);
pointo=[];
for k=ko'
pointo=[pointo;inplnk(inpptr(k))]
end
pointi=[];
for k=ki'
pointi=[pointi;outlnk(outptr(k))]
end
nx=size(state.x,'*');
nu=0; for k=pointi', nu=nu+size(state.outtb(k),'*'), end
ny=0; for k=pointo', ny=ny+size(state.outtb(k),'*'), end
if rhs<3 then
x0=zeros(nx,1);u0=zeros(nu,1);
else
if size(x0,'*')<>nx | size(u0,'*')<>nu then
error('u0 or x0 does not have the correct size')
end
end
if rhs==4 then
del = param(1)+param(1)*1d-4*abs([x0;u0])
t=param(2)
else
del=1.d-6*(1+1d-4*abs([x0;u0]))
t=0
end
x0=x0(:);u0=u0(:)
state.x=x0;
Uind=1
for k=pointi'
state.outtb(k)=matrix(u0(Uind:Uind+size(state.outtb(k),'*')-1),size(state.outtb(k)));
Uind=size(state.outtb(k),'*')+1;
end
[state,t]=scicosim(state,t,t,sim,'linear',[.1,.1,.1,.1]);
Yind=1
for k=pointo'
y0(Yind:Yind+size(state.outtb(k),'*')-1)=state.outtb(k)(:);
Yind=size(state.outtb(k),'*')+1
end
xp0=state.x;
zo0=[xp0;y0];
F=zeros(nx+ny,nx+nu);
z0=[x0;u0];
zer=zeros(nx+nu,1);
for i=1:nx+nu
dz=zer;dz(i)=del(i);
z=z0+dz;
state.x=z(1:nx);
Uind=nx+1
for k=pointi'
state.outtb(k)=matrix(z(Uind:Uind+size(state.outtb(k),'*')-1),size(state.outtb(k)));
Uind=size(state.outtb(k),'*')+1;
end
[state,t]=scicosim(state,t,t,sim,'linear',[.1,.1,.1,.1]);
zo=[]
Yind=1
for k=pointo'
zo(Yind:Yind+size(state.outtb(k),'*')-1)=state.outtb(k)(:);
Yind=size(state.outtb(k),'*')+1
end
zo=[state.x;zo];
F(:,i)=(zo-zo0)/del(i);
end
sys=syslin('c',F(1:nx,1:nx),F(1:nx,nx+1:nx+nu),F(nx+1:nx+ny,1:nx),F(nx+1:nx+ny,nx+1:nx+nu));
endfunction