How do I preallocate symbolic matrix?

I got the warning of preallocation when I tried to change the size of my 1*n symbolic array (elements are symbolic expressions) every time I added a new element. So I wonder how do I allocate symbolic array like zeros(n) in numeric array? Does zeros(m,n,'sym') or sym(zeros(m,n)) work or whatever really works and would increase speed?

Answer 1

[Walter Roberson]

sym(zeros(m,n)) is good and would increase your speed.

[Hernán Moreno]

helpful, thanks :D