lookup table error in simulink

Hello I am trying to model a 2D lookup table in simulink. I am calling the break points and table data from workspace. When i run it it shows an error as "the number of dimensions specified by the 'Table data' parameter (1) must match the 'Number of table dimensions' parameter value (2)." but when I check the table dimensions are table data: 1x9000 and break point 1 : 1x9000 and break point 2: 1x9000 all are same. But still I am getting this error. Please guide me through it.

Answer 1

[Sai Sri Pathuri]

Check whether you have set Number of table dimesions to 1, since your data is one-dimensional

[vishnuvardhan naidu tanga]

Hello @Sai Sri Pathuri,

thank you for the reply. Actually I am trying to obtain the results with respect to two parameters.the code is as follows:

a = 1000;
b = 0.1;
h_out = zeros(1,((a-1)/b));
L = length(h_out);

for i = 1:L

    
    T(i)= 1+b*i;
    p(i) = 1+b*i;

    h_out(i) = XSteam('h_pT', p(i), T(i)); 
end    

so h_out depends on two variables T and P, so i need two break points T and P to define h_out. the code basically extracts the h_out from xsteam and saves into workspace, which is then again called in simulink. Is there any way to deal with it

[Sai Sri Pathuri]

Did you run the code before adding these values in dialog box?

Can you click on errors at Breakpoints 1 and Breakpoints 2 beside p and T respectively and share the errors here?

[vishnuvardhan naidu tanga]

yes i run the code. when i run the code the break points are updated from the data base. the error marks in break points are eliminated. But the system wont run because of the following error:

In block 'SH', the number of dimensions specified by the 'Table data' parameter (1) must match the 'Number of table dimensions' parameter value (2).

[Sai Sri Pathuri]

Set Number of table dimensions (I highlighted it in above screenshot) to 1 in the dialog box, because your input is one-dimensional

Answer 2

[Johannes Lips]

The problem, which was not properly addressed in the previous answer, is the table data itself, not the dimensionality parameter.

For the 2D lookup table, you ought to use a row vector of length n1 for breakpoints 1, a row vector of length n2 for breakpoints 2, and a 2D matrix with size n1 x n2 for the table data.

Preprocessing (reshape or interpolate) of the 1x9000 data of this question is necessary to obtain the required inputs for the 2D lookup table block.

rangeX1 = %choose based on data e.g. min(x1):stepx1:max(x1)
rangeX2 = %similar
[X1grid, X2grid] = meshgrid(rangeX1, rangeX2);

% Create the scattered interpolant for your original data
F = scatteredInterpolant(x1, x2, y, 'linear', 'none');

% Evaluate the function on the grid
Ygrid = F(X1grid, X2grid);

Then use rangeX1, rangeX2 and Ygrid for the breakpoints and table data.