Example

> a = rand(3,3)+rand(3,3)*1j
 a =
 matrix columns 1 thru 3
          0.362 + 0.782i         0.00543 + 0.52i          0.83 + 0.0106i
          0.148 + 0.341i          0.222 + 0.161i        0.00526 + 0.414i
          0.879 + 0.461i           0.98 + 0.975i          0.246 + 0.233i

> symm(a)
 matrix columns 1 thru 3
              0.362 + 0i        0.0766 + 0.0896i          0.855 - 0.225i
        0.0766 - 0.0896i              0.222 + 0i           0.493 - 0.28i
          0.855 + 0.225i           0.493 + 0.28i              0.246 + 0i

> norm(a)
     2.23
> norm(a,"2")
     2.08
> norm(a,"f")
     2.26
> norm(symm(a))
      1.7
> norm(symm(a),"2")
     1.38
> norm(symm(a),"f")
     1.57