how to define initial dimention to variable that has various dimention?

Question

I define matlab function block that compute continuos wavelet transfrom(CWT) in simulink and have problem to initialize output of cwt, because the wavelet coefficients have various dimention in each time step.

1. how should i define initial value of cwt output?

2. and how should i write that every 0.5 second pass, compute cwt?(not in all time steps)

my FCN code:

function [c,f]=cwtendpadding(x)
coder.extrinsic('cwt')
c=zeros(401)+0i;
f=nan(200,1);
global x_hist x_ind
x_hist(x_ind)=x;
x_ind = x_ind+1;
if x_ind>=100
[c,f]=cwt(x_hist(1:x_ind-1),'amor',1000,'ExtendSignal',false);
end
end

error: Size mismatch for MATLAB expression 'c'. Expected = 401x401 Actual = 38x99