Undefined function 'diag' for input arguments of type 'cell'.

I am trying to run a code given by Felipe Uribe Castillo

%%% function to generate c_ijk with dimension M and order p
%% using symbolic toolbox
function c = c_ijk_sym(M,p)
M=3
p=1

%% Define the number of RVs in sym
x = cell(1,M);
for j = 1:M
    x{j} = sym(sprintf('xi_%d',j));
end

%% Generate Hermite pols using the ’Hermite_PC’ function
%% defined in Section 3.4 of this document
[~,Psi,PsiSqNorm,P] = Hermite_PC(M,p)

%% Procedure
dw = @(x) exp(-0.5*x^2)/sqrt(2*pi); %% Gaussian measure
c = cell(M,1)
c{1} = diag(PsiSqNorm); %% c_{0jk}
tic;
for i = 1:M
    c{i+1} = sparse(P,P);
    for j = 1:P
        for k = 1:P
            msg = fprintf('C_{%d,%d,%d}',i,j,k);
            cijk = x{i}*Psi{j}*Psi{k};
            for l = 1:M
                cijk = int(cijk*dw(x{l}),x{l},-inf,inf);
                if cijk == 0
                    break;
                end
            end
            c{i+1}(j,k) = double(cijk);
            fprintf(repmat('\b',1,msg));
        end
    end
end
toc;
return;

I am getting the following error:

Undefined function 'diag' for input arguments of type 'cell'.

Error in c_ijk_sym (line 20)

c{1} = diag(PsiSqNorm); %% c_{0jk}

please help.

[Torsten]

The error message is pretty clear, isn't it ?

"diag" cannot be applied to a variable of type "cell", and "PsiSqNorm" seems to be of this type.

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/mlc-downloads/downloads/submissions/53276/versions/1/previews/ssfem_eb_beam/Hermite_PC.m/index.html

The output PsiSqNorm is the fifth output of that function, but your named output with that name is the fourth output of the call.