Error using c2d extraction for block initialization

    if order == 2
    sys1 = tf([1], [1/(omega^2) 1.4142/omega 1]);
    d_sys = c2d(sys1,Ts);
    x = d_sys.num{1} %%error is here
    y = d_sys.den{1} %%error is here
    set_param([gcb '/filter_1'], 'SampleTime', 'Ts');
    set_param([gcb '/filter_1'],'Numerator', 'x', 'Denominator', 'y')
elseif order == 1
    sys1 = tf([1], [1/omega 1]);
    d_sys = c2d(sys1,Ts);
    x = d_sys.num{1} %%error is here
    y = d_sys.den{1} %%error is here
    set_param([gcb '/filter_1'], 'SampleTime', 'Ts', 'Numerator','x','Denominator', 'y');
else
    fprintf('Error');
end

In my code I am initializing a mask for a block I made. "filter_1" is a discrete time transfer function, and I am trying to set the numerator and denominator parameters. There error I am recieving is:

"Error in 'butter/Subsystem': Initialization commands cannot be evaluated. Caused by: Invalid setting in 'butter/Subsystem/filter_1' for parameter 'Numerator'."

I am just trying to extract the numerator and denominator coefficients from 'd_sys' and use those to intialize my block. Help! Thanks in advance.

Answer 1

[Drew Davis]

I am assuming the code you posted lives only in the mask initialization of your block. In that case the variable 'x' and 'y' go out of scope after the block initialization is performed. You can ensure that the variables 'x' and 'y' are put in the base workspace by using the evalin or assignin command inside the mask.

Alternatively, you can set the numerator/denominator to their respective numeric value by performing the following command:

set_param([gcb '/filter_1'],'Numerator', ['[' num2str(x) ']'], 'Denominator', ['[' num2str(y) ']'])