dimensions of matlab function block

Hello,

I have the following code

function [Fx1, Fy1, Fx2, Fy2, Fx3, Fy3, Fx4, Fy4]= fcn(u)
%Parameter laden
Moseberg;
F_max = (1:4);


%Input definition
% target trajectory
Fx_V = u(1);
Fy_V = u(2);
Mz_V = u(3);

%calculated friction border
F_max(1) = u(4);
F_max(2) = u(5);
F_max(3) = u(6);
F_max(4) = u(7);


y = @m;

but I keep getting these errors.

This text contains non-empty top-level expressions. It appears to be a script.

Function 'Moseberg.m' (#51.0.0), line 0, column 0:
""
Launch diagnostic report.
Component:MATLAB Function | Category:Coder error
Errors occurred during parsing of MATLAB function 'FTR_diskret/CarMaker/VehicleControl/FTR1/Fahren/Aufteilung der Überaktuierung /Kräfteaufteilung/kritischer Fahrbereich/MATLAB Function'
Component:MATLAB Function | Category:Coder error
Simulink cannot determine sizes and/or types of the outputs for block 'FTR_diskret/CarMaker/VehicleControl/FTR1/Fahren/Aufteilung der Überaktuierung /Kräfteaufteilung/kritischer Fahrbereich/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs.
Component:MATLAB Function | Category:Coder error
Compilation of model 'FTR_diskret' failed while trying to resolve underspecified signal dimensions.
  Suggested Actions
 Enable 'warning' or 'error' diagnostics for the list of underspecified signal dimensions.
 Open
Caused by:
Simulink cannot determine sizes and/or types of the outputs for block 'FTR_diskret/CarMaker/VehicleControl/FTR1/Fahren/Aufteilung der Überaktuierung /Kräfteaufteilung/kritischer Fahrbereich/MATLAB Function' due to errors in the block body, or limitations of the underlying analysis. The errors might be inaccurate. Fix the indicated errors, or explicitly specify sizes and/or types for all block outputs. 
Error occurred in 'FTR_diskret/CarMaker/VehicleControl/FTR1/Fahren/Aufteilung der Überaktuierung /Kräfteaufteilung/kritischer Fahrbereich/MATLAB Function'. 

Can someone help me how to fix the dimensions?

Answer 1

[Walter Roberson]

It looks to me as if MATLAB Function Block cannot invoke scripts .

https://www.mathworks.com/matlabcentral/answers/419455-matlab-function-block-creaed-from-simulink-calling-an-m-script#answer_338279

Your Moseberg appears to be a script.

coder.extrinsic('Mosebergfct')
Mosebergfct;
coder.extrinsic('ParameterSarah')
ParameterSarah;

You are using Mosebergfct and ParameterSarah as if they are scripts as well. You should convert them into functions (returning appropriate variables) that are called each time, or else convert them into functions that you call once at the beginning and pass the values around.

Simulink Code Generator demands a lot of transparency.

Answer 2

[Chris Verhoeven]

You should end the function with end. And then you can call upon the function in a matlab file which is located in the same folder or in the same script.

function [Fx1, Fy1, Fx2, Fy2, Fx3, Fy3, Fx4, Fy4]= fcn(u)

%% code

end

[Sarah Kern]

Thank you very much I did it.

@m is my function in another file in the same folder.

But it still determine the size and type of the out put.

Any more ideas?

[Chris Verhoeven]

To be honest, i'm not sure what your problem is exactly. Could you try to explain it better? And have you used functions before, because to me it seems like you might not understand the purpose of a function. The function requires an input and an output and it does not know anything else except the input and the code it contains.

This is useful if you want to use a piece of code multiple times. For example if you want to calculate the side C of a triangle where C represents the length of the hypotenuse and A and B the lengths of the triangle's other two sides.

clear all, clc

side1 = 1;
side2 = 2;

side3 = pythagoras(side1,side2) 


%% Function this can be in a seporate matlab function file 
% or at the bottom of your script 
function [C] = pythagoras(A,B)
C = sqrt(A.^2+B.^2) %pythagoras theorem
end

Of course this is a really simple function but I hope you get the idea. If this is not sufficient, please make your problem clear so I can help you better :)

~Chris

[Sarah Kern]

I am sorry, I try to be clearer

I have an analytical optimization

function [Fx1, Fy1, Fx2, Fy2, Fx3, Fy3, Fx4, Fy4] = myfunction

ParameterSarah;

%Definition der Rad-Fahrzeug-Kopplung

G = [1,0,1,0,1,0,1,0;

0,1,0,1,0,1,0,1;

-w_l,l_v,w_r,l_v,-w_l,-l_h,w_r,-l_h];

%Definition des Rechtsannihilators G_ra

G_Ra = [1,0,0,0,-((l_v+l_h)/(w_l+w_r)); 0,0,1,0,0; 0,1,0,0,(l_v+l_h)/(w_l+w_r); 0,0,-1,0,-1; -1,0,0,0,0; 0,0,0,1,1; 0,-1,0,0,0; 0,0,0,-1,0];

%Definition der Moore-Penrose Inverse G_plus

G_Moore = transpose(G)*inv((G*transpose(G)));

%Definition der Gewichtungsmatrix Q

Q = [1/F_max/(1) 0 0 0 0 0 0 0;

0 1/F_max(1) 0 0 0 0 0 0;

0 0 1/F_max(2) 0 0 0 0 0;

0 0 0 1/F_max(2) 0 0 0 0;

0 0 0 0 1/F_max(3) 0 0 0;

0 0 0 0 0 1/F_max(3) 0 0;

0 0 0 0 0 0 1/F_max(4) 0;

0 0 0 0 0 0 0 1/F_max(4)];

%Bestimmung der fünf Kraftparameter für die minimale Kraftschlussausnutzung

%deltax = -inv((transpose(G_Ra)*Q*G_Ra))*transpose(G_Ra)*Q*G_Moore*v;

%Bestimmung des realen Stellvektors

%y=[Fx1, Fy1, Fx2, Fy2, Fx3, Fy3, Fx4, Fy4]^T

%y=G_Moore*F_soll+G_Ra*deltax;

F_soll = [Fx_V; Fy_V; Mz_v];

myfunction = (G_Moore-G_Ra*inv((transpose(G_Ra)*Q*G_Ra))*transpose(G_Ra)*Q*G_Moore)*F_soll;

Fx1 = myfunction(1);

Fy1 = myfunction(2);

Fx2 = myfunction(3);

Fy2 = myfunction(4);

Fx3 = myfunction(5);

Fy3 = myfunction(6);

Fx4 = myfunction(7);

Fy4 = myfunction(8);

end

and I want to use it in my matlab function block

function [Fx1, Fy1, Fx2, Fy2, Fx3, Fy3, Fx4, Fy4]= fcn(u)

%Parameter laden

coder.extrinsic('Mosebergfct')

Mosebergfct;

coder.extrinsic('ParameterSarah')

ParameterSarah;

F_max = (1:4);

%Input definition

% target trajectory

Fx_V = u(1);

Fy_V = u(2);

Mz_V = u(3);

%calculated friction border

F_max(1) = u(4);

F_max(2) = u(5);

F_max(3) = u(6);

F_max(4) = u(7);

Fx1 = zeros;

Fy1 = zeros;

Fx2 = zeros;

Fy2 = zeros;

Fx3 = zeros;

Fy3 = zeros;

Fx4 = zeros;

Fy4 = zeros;

y = @myfunction;

end

I read that in a matlab function block I have to define the output dimensions first and haope I can do this with the Fx1 = zeros. So far I always get the error that there is to less information and the output dimensions can not be defined

Answer 3

[Chris Verhoeven]

You dont have to define your output as Fx1 = zeros. As long ase somewhere in the output variables are calculated somewhere in the function its fine.

But i'm confused. You have two functions in this file, but no code that uses the functions. Also the first function "myfunction" has no input requirements (so why use a function) and calls itself later in the same function "Fx1 = myfunction(1);" and here you use a input variable of 1 but you didn't define that the function needed an input in the first place. Calling upon a function in it's own function is not possible since it'll create an infinite loop.

Functions are there to make things easier, but they are not always necessary to use.

~Chris

Answer 4

[Chris Verhoeven]

This link might be useful https://nl.mathworks.com/help/matlab/ref/function.html

[Sarah Kern]

Its in a matlab function block, so all I need the function to do to take the inputs which I defined as the vector u and calculate the Fxis. I am not allowed to define another function in the matlab function block, so I needed to create another skript with the second function. And without the definition Fx=zeros, Simulink couldnt handle the function outputs. What do you mean I am stuck in the loop?