how to fix this error 'Index exceeds array dimensions. Index value 3 exceeds valid range [1-2] for array 'a'. '

HI guys, I have some problem during running the code below and it give me the error

• Index exceeds array dimensions. Index value 3 exceeds valid range [1-2] for array 'a'. Error in 'TEST/TEST' (line 18) if a(i)> 0

This code is the code for computiong the parameter k for the scalar reference governor. and Hx and Hv is the maximal admissible output sets(MAS) with the matrices A,B,C,D hope can get some help to fix this code form your all.

function v = SRG_new(v_previous, r)
  A=[0 1;-275.5 -21.22];
  B=[0;1];
  C=[11.02 275.5];
  D=0;
  I=eye(2);
  Hx=(C*A); 
  Hv= C*((I-A)*((I-A)^-1)*B+D); 
  s=350; %s=max_output
  a=Hx*(r-v_previous);
  b=s-Hx-Hv*v_previous;
  k=1;
 
for i=1:100
    if a(i)> 0
        k=min(k, b(i)/a(i));
    end       
end
k=max(k,0);

v=v_previous + k*(r-v_previous);
 end

[KSSV]

What input you have tried?

v_previous, r

The error is clear, a could be a scalar value and you are treating it as a vector of length 100.

[Walter Roberson]

That does not look like a MATLAB error message. An Octave error message maybe.

[CHEW Yen LI]

@KSSV HI , the input that I tried is the step input and fyi me is use the matlab function block in the simulink to code this .

Answer 1

[Walter Roberson]

Replace the loop with

mask = a > 0;
a = a(mask);
b = b(mask);
if isempty(a)
    k = 1;
else
    k = max(0, min(a./b));
end

[CHEW Yen LI]

@Walter Roberson Hi ,thx for help me slove the error , but I not so understand the code u suggest to me, can u give me some explanation ?

[Walter Roberson]

Okay then, change your code from

  k=1;
 
for i=1:100
    if a(i)> 0
        k=min(k, b(i)/a(i));
    end       
end
k=max(k,0);

to

  k=1;
 
for i=1:length(a)
    if a(i)> 0
        k=min(k, b(i)/a(i));
    end       
end
k=max(k,0);

[CHEW Yen LI]

@Walter Roberson thx for help me solve the error