# Possible to use algebraic expression as array subscript? **URL:** \ **Category:** Uncategorized\ **Created:** [September 6, 2020, 5:02pm UTC](https://fortran-lang.discourse.group/t/possible-to-use-algebraic-expression-as-array-subscript/291 "2020-09-06T17:02:00Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![lanast](https://avatars.discourse-cdn.com/v4/letter/l/cdc98d/32.png) [@lanast](https://fortran-lang.discourse.group/u/lanast)\ **Post date:** [September 6, 2020, 5:02pm UTC](https://fortran-lang.discourse.group/t/possible-to-use-algebraic-expression-as-array-subscript/291/1 "2020-09-06T17:02:00Z")
Dear Fortran community, is it possible to use an algebraic expression of integers as the subscripts of an array `A`, for accessing or for manipulating elements of an array? I would like to implement following code: ` DO i = 1,N1` ` DO j = 1,N2` ` A((i+j),((i-1)*(j-1)+j)) = ...` ` END DO` ` END DO` It appears that the compiler requires, that the resulting indices are not out of the range which was used to initalize the matrix. Thank you ---
**Author:** ![billlong](https://avatars.discourse-cdn.com/v4/letter/b/71e660/32.png) [@billlong](https://fortran-lang.discourse.group/u/billlong)\ **Post date:** [September 6, 2020, 6:19pm UTC](https://fortran-lang.discourse.group/t/possible-to-use-algebraic-expression-as-array-subscript/291/2 "2020-09-06T18:19:35Z")
Yes. Integer valued expressions are fine as subscript values. Those values are required to be within the range [lower\_bound, upper\_bound] for each dimension. That is a standard requirement, which some compilers enforce. ---
**Author:** ![lanast](https://avatars.discourse-cdn.com/v4/letter/l/cdc98d/32.png) [@lanast](https://fortran-lang.discourse.group/u/lanast)\ **Post date:** [September 7, 2020, 10:01am UTC](https://fortran-lang.discourse.group/t/possible-to-use-algebraic-expression-as-array-subscript/291/3 "2020-09-07T10:01:28Z")
Thank you @billlong, this clarifies it