function Ret = pare_varpro_hook (what, vn, OPTIONS, INC);%PARE_VARPRO_HOOK       Hook for varpro ellipse fit  %% Ret = pare_varpro_hook (what, vn, OPTIONS, INC);% Hook for the 'varpro' routine, returns data depending on 'what'.% given data is Y = [x-coord(1:m,1); y-coord(1:m,1)]% estimation function is % a*Phi(1) + b*Phi(2) + z(1)*Phi(3) + z(2)*Phi(4)%% what: kind of data needed (see 'varpro')% vn: non-linear parameters% OPTIONS: same as options passed to 'varpro' routine% INC: incidence matrix, for what == 'DPhi_Inc' only%% Ret: see 'varpro'  m = size(vn,1) - 1;  if (strcmp(what,'Phi') | strcmp(what,'DPhi') | ...      strcmp(what,'DPhi_Inc')),    C = cos (vn(1:m));    S = sin (vn(1:m));    c = cos (vn(m+1));    s = sin (vn(m+1));  end        if    (strcmp(what, 'Phi')),    Ret = [ c*C, -s*S,  ones(m,1), zeros(m,1);            s*C,  c*S, zeros(m,1),  ones(m,1)];  elseif (strcmp(what, 'DPhi')),    Ret = [];    for i = 1:m,      J = zeros(2*m,4);      J(i,1)   = -c*S(i);      J(i+m,1) = -s*S(i);      J(i,2)   = -s*C(i);      J(i+m,2) =  c*C(i);      Ret = [Ret, J];    end    Ret = [Ret, [-s*C, -c*S, zeros(m,2); c*C, -s*S, zeros(m,2)]];  elseif (strcmp(what, 'DPhi_Inc')),    %% INC(i,j) if column phi(i)/dalpha(j) should be added.    p   = ones(1,4)*INC*ones(m+1,1);    Ret = zeros(2*m,p);    p   = 0;    for i = 1:m,      if (INC(1,i)), p = p+1; Ret(i,p) = -c*S(i);                               Ret(i+m,p) = -s*S(i);       end;      if (INC(2,i)), p = p+1; Ret(i,p) = -s*C(i);                               Ret(i+m,p) =  c*C(i);       end;      if (INC(3,i)), p = p+1; end;      if (INC(4,i)), p = p+1; end;    end    i = m+1;    if (INC(1,i)), p = p+1; Ret(:,p) = [-s*C;  c*C]; end;    if (INC(2,i)), p = p+1; Ret(:,p) = [-c*S; -s*S]; end;    if (INC(3,i)), p = p+1; end;    if (INC(4,i)), p = p+1; end;  elseif (strcmp(what, 'Inc')),    Ret = [ones(2,m+1); zeros(2,m+1)];  else    str = sprintf ('unknowm: command %s.', what);    error (str);  endend % pare_varpro_hook