Solving an equation with symbolic matrix

I've tried solving eq1 in the following program.

The right answer is w = -D*lambda*unos

%start
unos=ones(2,1)

unos = 2×1

1 1

ceros=zeros(2,1)

ceros = 2×1

0 0

E = symmatrix('E',2)

E = 

D=inv(E)

D = 

w=symmatrix('w',[2,1])

w = 

eq1= w + D*lambda*unos==ceros

Unrecognized function or variable 'lambda'.

solve(eq1,w)
%end

The right answer is w = -D*lambda*unos

But instead, I get the following message:

Check for incorrect argument data type or missing argument in call to function 'solve'.

Please help

Answer 1

[Torsten]

https://uk.mathworks.com/matlabcentral/answers/1918100-error-using-solve-with-symmatrix-equation

[Juan Ignacio Peña]

Thank you, Torsten. Thus, the function solve doesn't support the symmatrix command.

As a result, I infer that it is not possible in Matlab to solve

eq1= w + D*lambda*unos==ceros

for any arbitrary matrices w and D of any size.

[Torsten]

You can use "symmatrix2sym" as suggested in the link.

Or you can define the matrices as syms right from the beginning.

[Juan Ignacio Peña]

Thank you, Torsten. I am interested in working with matrices as whole variables. I mean, considering matrices or vectors of generic size and with given assumptions (like symmetric, positive definite, etc), but without knowing the exact dimensions and elements. In my example, D is the inverse of a symmetric matrix, and I'm looking for the answer in terms of the matrix and not its elements.

As far as I understand, symmatrix2sym(D) converts a symbolic matrix variable D to an array of symbolic scalar variables S. I'm not interested in the elements of D. I am interested in working with D as a specific variable (of any dimension).

[Torsten]

Ok, then it doesn't seem possible in MATLAB.