error in zpk function

Hi to everyone , i can't understand why matlab printthis error message ""

def = [
      1        % IngressoTipo  1
      1        % IngressoPar   2
      1        % Uscita        3
      0.0      % P_min         4
      1        % P, P_cur      5
      10       % P_max         6
      1        % A, A_cur      7
      1        % delta, delta_cur 8
      4.5      % R1, R1_cur       9
      5        % R2, R2_cur     10
      0.0      % h10, h10_cur   11
      0.0      % h2, h2_cur      12
      ];
%END PROJECT'S CODE

g     = 9.81;

%BEGIN PROJECT'S CODE
h10   = def(11);
h20   = def(12);
A     = def(7);
delta = def(8);
R1    = def(9);
R2    = def(10);


SetPoint= get(handles.SetPoint, 'Value');

Mu=str2num(str2mat(get(handles.Mu_string,'String')));
Nx=str2num(str2mat(get(handles.Nx_string,'String')));
Dx=str2num(str2mat(get(handles.Dx_string,'String')));
% END PROJECT'S CODE 




% Calcolo costanti di tempo nel punto di eq.
F = [-delta*g/(A*R1)               0; 
      delta*g/(A*R1) -delta*g/(A*R2)];
Tau = TimeConstantLTI(F);
% valore di default in caso di fallimento calcolo
if isnan(Tau), Tau = 0.1; end
Tau = min(100, Tau);  % sogliatura per evitare sim troppo lunghe


% Esporta tutte le variabili nel Workspace per permettere a Simulink
% di averne visibilità
vars = {'A', A; 'delta', delta; 'g', g; 'R1', R1; 'R2', R2; 'h10', h10; 'h20', h20;'SetPoint',SetPoint;'Mu',Mu;'Nx',Nx;'Dx',Dx};
for i = 1 : size(vars, 1)
  name = vars(i, 1);
  value = vars(i, 2);
  assignin('base', name{1}, value{1}); 
end

% sistema 
% Preparazione matrici F, G, H, J = 0
F = [-delta*g/(A*R1)               0; 
      delta*g/(A*R1) -delta*g/(A*R2)];
G = [1/A; 
       0];
   
H = [0 +1];
J = zeros(size(H, 1), size(G, 2));
sysProcesso = ss(F, G, H, J);
figure(1),bode(sysProcesso);
figure(2),nyquist(sysProcesso);
[NumP, DenP,GainP] = zpkdata(sysProcesso);

numAnello=[Nx cell2mat(NumP)];
denAnello=[Dx cell2mat(DenP)'];
guadagno=GainP*Mu;
fAnello=[mat2cell(numAnello,size(numAnello,1),size(numAnello,2)) ,mat2cell(denAnello,size(denAnello,1),size(denAnello,2)) , guadagno];
sysAnello=zpk(fAnello(1),fAnello(2),fAnello(3));
bode(sysAnello);
nyquist(sysAnello);

[Walter Roberson]

What is the error message? We do not have your graphics structure so we cannot test it out

[Andrea Gusmara]

The value of the "K" property must be a numeric array.

Answer 1

[Andrea Gusmara]

Mu=str2num(str2mat('[3]'));

Nx=str2num(str2mat('[10]'));

Dx=str2num(str2mat('[10]'));

Answer 2

[Walter Roberson]

fAnello=[mat2cell(numAnello,size(numAnello,1),size(numAnello,2)) ,mat2cell(denAnello,size(denAnello,1),size(denAnello,2)) , guadagno];

With all those mat2cell(), we can tell that fAnello is going to be a cell array.

sysAnello=zpk(fAnello(1),fAnello(2),fAnello(3));

That passes cells extracted from fAnello into zpk, as cells

https://www.mathworks.com/help/control/ref/zpk.html

"In the SISO case, Z and P are the vectors of real- or complex-valued zeros and poles, and K is the real- or complex-valued scalar gain:"

Not cells in that case.

For the MIMO case,

"Z and P are cell arrays of vectors with as many rows as outputs and as many columns as inputs, and K is a matrix with as many rows as outputs and as many columns as inputs. [...] K(i,j) specifies the (scalar) gain of the transfer function from input j to output i."

So Z and P can be cells for the MIMO case, but K must be numeric. You are passing in a cell for K.