Sum of elements of a multidimensional symbolic array

I have a multidimensional array whose entries are polynomials. I would like to obtain the sum of all elements in the array. I know that is it is a vector is just need to use sum, if it is a matrix I would use sum twice, if it is a 3 array I would use sum three times and so on. In MATLAB, it worked fine up to a matrix, but when I tried the command sum for a 3 array it gave me the message:

Error using mupadmex Error in MuPAD command: Input arguments must be 2-D.

Error in sym/privUnaryOp (line 826) Csym = mupadmex(op,args{1}.s,varargin{:});

Error in sym/sum (line 59) s = privUnaryOp(A, 'symobj::prodsum', '_plus');

Is there any way around this?

Answer 1

[Azzi Abdelmalek]

syms x
a(1,1,1)=x
a(1,1,2)=x^2
a(1,1,3)=x^3
out=sum(a(:))

[Farid Salazar Wong]

Simpler than I thought. Thanks!