Too many input arguments - idgrey

Hello everyone,

I'm trying to define a grey box model for parameters identification

pars = {ms; mu; meq; ceq; ks; ku; cu; km; cm};

linear_model = idgrey('QC_rot_func',pars,'c');

but I'm getting this error when running the model:

Error using idgrey (line 367)

The ODE function "QC_rot_func" could not be evaluated successfully using the given set of parameters, sample time

and optional arguments. The error message generated during the evaluation was:

Too many input arguments.

Error in main (line 175)

linear_model = idgrey('QC_rot_func',pars,'c');

The function 'QC_rot_func' is the following:

function [A,B,C,D] = QC_rot_func(pars,Ts)

ms = pars(1);

mu = pars(2);

meq = pars(3);

ceq = pars(4);

ks = pars(5);

ku = pars(6);

cu = pars(7);

km = pars(8);

cm = pars(9);

A = [0 0 0 1 -1 0;

0 0 0 0 1 -1;

0 0 0 0 0 1;

(-ks/ms-km/ms) -ks/ms 0 -cm/ms cm/ms 0;

(ks/mu+km/mu+km/meq) ks/mu -ku/mu (cm/mu+cm/meq) (-cm/mu-cm/meq-ceq/meq) (-cu/mu+ceq/meq);

(ks/mu+km/mu) ks/mu -ku/mu cm/mu -cm/mu -cu/mu];

Bd = [0; 0; -1; 0; cu/mu; cu/mu];

Bdlt = [0; 0; 0; 1/ms; 0; 0];

Bu = [0; 0; 0; 0; 1/meq; 0];

B = [Bd Bdlt Bu];

C = [A(4,:); A(6,:); A(1,:)+A(2,:)];

D = [B(4,:); B(6,:); B(1,:)+B(2,:)];

end

What is the problem in this code? If I try to run the function with parameters as input, I get di A B C D matrices as expected.

Thank you.

Answer 1

[Cris LaPierre]

The error is in how you define your odefun. Although you pass in all the parameters in a single cell array, your function declaration must still list each variable separately. See this doc example.

Here's an example that runs here.

ms = 5;
mu = 4;
meq = 3;
ceq = 2;
ks = 3;
ku = 4;
cu = 5;
km = 6;
cm = 5;
pars = {ms; mu; meq; ceq; ks; ku; cu; km; cm};
linear_model = idgrey(@QC_rot_func,pars,'c')

linear_model =
  Continuous-time linear grey box model defined by @QC_rot_func function:
      dx/dt = A x(t) + B u(t) + K e(t)
       y(t) = C x(t) + D u(t) + e(t)
 
  A = 
            x1       x2       x3       x4       x5       x6
   x1        0        0        0        1       -1        0
   x2        0        0        0        0        1       -1
   x3        0        0        0        0        0        1
   x4     -1.8     -0.6        0       -1        1        0
   x5     4.25     0.75       -1    2.917   -3.583  -0.5833
   x6     2.25     0.75       -1     1.25    -1.25    -1.25
 
  B = 
           u1      u2      u3
   x1       0       0       0
   x2       0       0       0
   x3      -1       0       0
   x4       0     0.2       0
   x5    1.25       0  0.3333
   x6    1.25       0       0
 
  C = 
          x1     x2     x3     x4     x5     x6
   y1   -1.8   -0.6      0     -1      1      0
   y2   2.25   0.75     -1   1.25  -1.25  -1.25
   y3      0      0      0      1      0     -1
 
  D = 
         u1    u2    u3
   y1     0   0.2     0
   y2  1.25     0     0
   y3     0     0     0
 
  K = 
       y1  y2  y3
   x1   0   0   0
   x2   0   0   0
   x3   0   0   0
   x4   0   0   0
   x5   0   0   0
   x6   0   0   0
 
  Model parameters:
   Par1 = 5
   Par2 = 4
   Par3 = 3
   Par4 = 2
   Par5 = 3
   Par6 = 4
   Par7 = 5
   Par8 = 6
   Par9 = 5
 
Parameterization:
   ODE Function: @QC_rot_func
   Disturbance component: none
   Initial state: 'auto'
   Number of free coefficients: 9
   Use "getpvec", "getcov" for parameters and their uncertainties.

Status:                                                         
Created by direct construction or transformation. Not estimated.
 

function [A,B,C,D] = QC_rot_func(ms, mu, meq, ceq, ks, ku, cu, km, cm, Ts)   
    A = [0 0 0 1 -1 0;
         0 0 0 0 1 -1;
         0 0 0 0 0 1;
         (-ks/ms-km/ms) -ks/ms 0 -cm/ms cm/ms 0;
         (ks/mu+km/mu+km/meq) ks/mu -ku/mu (cm/mu+cm/meq) (-cm/mu-cm/meq-ceq/meq) (-cu/mu+ceq/meq);
         (ks/mu+km/mu) ks/mu -ku/mu cm/mu -cm/mu -cu/mu];
    Bd = [0; 0; -1; 0; cu/mu; cu/mu];
    Bdlt = [0; 0; 0; 1/ms; 0; 0]; 
    Bu = [0; 0; 0; 0; 1/meq; 0]; 
    B = [Bd Bdlt Bu];
    C = [A(4,:); A(6,:); A(1,:)+A(2,:)];
    D = [B(4,:); B(6,:); B(1,:)+B(2,:)];
end

[Gennaro Sorrentino]

Problem solved defining the function as yours, thank you very much!