MATLAB Fcn not yet supported by Simulink coder

I am using "MATLAB Fcn " module in Simulink. But when I am trying to build my code it gives me an error message that ""MATLAB Fcn" is not yet supported by Simulink Coder". The code is given as follows:

function yd=roll(rollangr,vd,t)
persistent N1;

x2=rollangr;
e2=x2-vd;

N1=[N1;e2];

But the code N1=[N1;e2]; is impassability. Can you guide me how to fix this error. Thank you very much.

[Nicolas Schmit]

Please post the complete error message.

[Shuyi shao]

Thank you very much.

The error message is "Undefined function or variable 'N1'. The first assignment to a local variable determines its class."

If I use "Interpreted MATLAB Fcn " module in Simulink, the code is correct. Since the restriction of simulation environment, I must use "MATLAB Fcn " module in Simulink.

the complete code as follows:

function yd=roll(rollangr,vd,t)
persistent N1;

      x2=rollangr;
  e2=x2-vd;

N1=[N1;e2];
a=((t*1000)/2)+1;
beta=0.001;
F1=0;

if a<=160 
    for i=1:a
          f=1;
            for k1=1:a
                f=(beta-(k1+1)+1)*f;
            end
            k2=k1+1;
            f=(-1)^(k2)*(f/(prod(1:k2)));
            F1=f*N1(i)+F1;
    end
else
    a=160; F1=0;
    for i=1:a
          f=1;
            for k1=1:a
                f=(beta-(k1+1)+1)*f;
            end
            k2=k1+1;
            f=(-1)^(k2)*(f/(prod(1:k2)));
            F1=f*N1(i)+F1;
    end

end 

yd=F1;
end

Answer 1

[Walter Roberson]

Your N1 is going to get larger every time roll() is called, by a size that is not obvious in the code 9since your inputs might be vectors or arrays.)

Simulink does not allow variables to grow to indefinite size in code generation, at least not without you having specifically turned on dynamic memory allocation for the variable.

If you need that variable to keep growing, then you should be using coder.varsize to signal the size, and you should probably be taking steps to place a maximum size on the variable, such as

if size(N1, 1) >= 200
   N1(1:199,:) = N1(end-199:end,:);
   N1(200,:) = e2;
   N1(201:end,:) = [];
else
  N1(end+1,:) = e2;
end

On the other hand, as you are not using N1 for further computation, and since your function has no way to output N1, why are you bothering to set N1 at all?

[Shuyi shao]

Thans for your help.

The simulation time is limited.If the code is used in "MATLAB Fcn " module in Simulink. The incorrect information is always prompted which is "Undefined function or variable 'N1'. Can you guide me how to fix this error. Thank you very much.

[Walter Roberson]

Look more closely at your code: you do not need more than 160 values saved. You should arrange your code to stop adding to the end of N1 after you reach 160.

I suggest that at the very least you change

N1=[N1;e2];
a=((t*1000)/2)+1;

to

a=((t*1000)/2)+1;
if a == 1
  N1 = e2;
else
  N1=[N1;e2];
end

[Shuyi shao]

I really appreciate your help. I use the code amended by you in "MATLAB Fcn " module in Simulink, however, there are still several mistakes. The incorrect information is "Size mismatch (size [1 x 1] ~= size [2 x 1]). The size to the left is the size of the left-hand side of the assignment.". The corresponding code is "N1=[N1;e2];".

If I use "Interpreted MATLAB Fcn " module in Simulink, the code is correct. Since the restriction of simulation environment, I must use "MATLAB Fcn " module in Simulink.

I am sorry to disturb you.

[Walter Roberson]

if a == 1
  N1 = zeros(160,1);
end
if a <= 160
  N1(a) = e2;
end

[Shuyi shao]

Thank you for your help. According to your suggestion, the code has been revised. However, there are still several mistakes when the code is used in "MATLAB Fcn " module in Simulink. If I use "Interpreted MATLAB Fcn " module in Simulink, the code is correct. The incorrect information is

Operands must be constants. Function 'roll_RBFNNS1' (#61.376.380), line 27, column 34:"1:k2"

The corresponding code is

f=(-1)^(k2)*(f/(prod(1:k2)));

Can you guide me how to fix this error. Thank you very much.

The complete code as follows:

function yd=rollSUMWUC(rollangr,vd,t)
persistent N1;
x2=rollangr;
e2=x2-vd;
beta=0.001;
F1=0;
a=((t*1000)/2)+1;
if a == 1
  N1 = zeros(160,1);
end
if a <= 160
  N1(round(a)) = e2;
end
if a<=160 
    for i=1:a
          f=1;
            for k1=1:a
                f=(beta-(k1+1)+1)*f;
            end
            k2=k1+1;
            f=(-1)^(k2)*(f/(prod(1:k2)));
            F1=f*N1(i)+F1;
    end
else
    a=160; F1=0;
    for i=1:a
          f=1;
            for k1=1:a
                f=(beta-(k1+1)+1)*f;
            end
            k2=k1+1;
            f=(-1)^(k2)*(f/(prod(1:k2)));
            F1=f*N1(i)+F1;
    end    
end 
yd=F1;
end

[Walter Roberson]

Change

prod(1:k2)

to

factorial(k2)

Better yet, rewrite:

    k2f = 1;
    for i=1:a
          f=1;
            for k1=1:a
                f=(beta-(k1+1)+1)*f;
            end
            k2=k1+1;
            k2f = k2f * k2;
            f=(-1)^(k2)*(f/k2f));
            F1=f*N1(i)+F1;
    end

[Shuyi shao]

Thank you very much for your help. I have one last question on the simulation of the code. The error message is "Error using cd Cannot CD to C:\Users\shaosy\AppData\Local\Temp (Name is nonexistent or not a directory)." for "MATLAB Fcn " module in Simulink. Can you guide me how to fix this error. Thank you very much.

[Walter Roberson]

The code is using tempdir() to attempt to create temporary files.

On MS Windows, MATLAB looks at the following, in order:

1. environment variable TMP
2. environment variable TEMP
3. environment variable USER_PROFILE
4. if none of the above exist, C:\temp

It appears to me that your system is configured with typical MS Windows settings for environment variables: a location such as "C:\Users\shaosy\AppData\Local\Temp" is quite typical. But for some reason that directory does not exist. If it is your personal system, then just go ahead and create the directory (provided you have spare storage space on the C drive.) If the system is being administered by someone else then they might have set it up expecting to use a different location for temporary files but forgot to publish a policy changing your environment variable to the appropriate location. If that is the situation for you, then inside MATLAB give the command

setenv('TMP', 'C:\some\suitable\directory\goes\here')
clear tempdir

[Shuyi shao]

Thank you very much for your warm help. According to your suggestion, there is still a mistake The error message "Error using cd Cannot CD to C:\some\suitable\directory\goes\here (Name is nonexistent or not a directory)." I am sorry to disturb you.

[Shuyi shao]

I am sorry to disturb you. The above problem has been settled. However, there is still sa mistake. The error message "persistent variable 'N1' is undefined on some execution paths". The corresponding code is "N1(a) = e2;" Can you guide me how to fix this error. Thank you very much.

The complete code as follows:

function yd=rollSUMWUC(rollangr,vd,t)
persistent N1;
x2=rollangr;
e2=x2-vd;
beta=0.001;
F1=0;
a=((t*1000)/2)+1;
if a == 1
N1 = zeros(160,1);
end
if a <= 160
N1(a) = e2;
end
if a<=160 
  for i=1:a
        f=1;
          for k1=1:a
              f=(beta-(k1+1)+1)*f;
          end
          k2=a+1;
          f=(-1)^(k2)*(f/(factorial(k2)));
          F1=f*N1(i)+F1;
  end
else
  a=160; F1=0;
  for i=1:a
        f=1;
          for k1=1:a
              f=(beta-(k1+1)+1)*f;
          end
          k2=a+1;
          f=(-1)^(k2)*(f/(factorial(k2)));
          F1=f*N1(i)+F1;
  end    
end 
yd=F1;
end

[Walter Roberson]

I am not sure. You could try changing

if a == 1
N1 = zeros(160,1);
end

to

if isempty(N1)
  N1 = zeros(160,1);
end