# subscripted variables

It is common in mathematics to use subscripted variables. We use the underscore to represent subscripts. If we haven't assigned a value to x we may simply start using it as a subscripted variable. The subscripts can be anything.
 i1 : x o1 = x o1 : Symbol i2 : x_4 o2 = x 4 o2 : IndexedVariable i3 : x_(2,3) o3 = x 2,3 o3 : IndexedVariable
The .. operator knows what to do with subscripted variables.
 i4 : x_10 .. x_20 o4 = (x , x , x , x , x , x , x , x , x , x , x ) 10 11 12 13 14 15 16 17 18 19 20 o4 : Sequence i5 : x_(1,1) .. x_(2,3) o5 = (x , x , x , x , x , x ) 1,1 1,2 1,3 2,1 2,2 2,3 o5 : Sequence
Values can be assigned to these variables with =.
 i6 : y_10 = 555; i7 : y_10 o7 = 555