I want to get the number of rows in doulble matrix but kept recieve an error

I have varible W1 type double and size 20x5

I workspace the varible looks like

Name    Value
W1        20x5

I can know the number of row by pressing length command but does not work with size command and shows an error any help please

With lenghth command

length(W1)
  ans =
      20

The tpye of the variable

class(W1)
   ans = 
        double

But with size does not work

 size(W1)
    Subscript indices must either be real positive integers or logicals.

Answer 1

[Walter Roberson]

You assigned something to a variable named size, so you will not be able to call the size() function until the variable size goes out of scope.