# Unable to find the exact dimension of an expression

I have defined a variable called y, this contains a huge equation, but when I look for the dimension of y it shows 3. How come a single expression has dimensions of 3? It is supposed to be 1 right?

y=39.25 ω^2 (1.00519 Subscript[a,4][1]^2+1.00102 Subscript[a,4][2]^2+2.19056 Subscript[a,4][1] Subscript[a,4][3]-1.07645 Subscript[a,4][2] Subscript[a,4][3]+1.5 Subscript[a,4][3]^2+0.55507 Subscript[a,4][1] Subscript[a,4][4]+1.54742 Subscript[a,4][2] Subscript[a,4][4]+1.5 Subscript[a,4][4]^2);;
Dimensions[y]
• Well, it is a product of three things. A one-dimensional list, of three elements. Jan 10, 2020 at 13:56
• Dimensions needs a full array as argument (see documentation) . If you apply it to a scalar surprising results like Dimension[a+b] (* 2*) occur. Jan 10, 2020 at 14:00
• It is a single expression right. Is it possible to make one expression with dimension 1 Jan 10, 2020 at 14:00
• Yes, something like {a +b} Jan 10, 2020 at 14:05
• Perhaps you would be interested in LeafCount which gives the total number of indivisible subexpressions. In this case, 78 Jan 10, 2020 at 15:53