Why not use the haskell guard syntax?
A_ij = | 1 if (i,j) ∈ E
| 0 otherwise
where
A ∈ ℝ^(n × n)
E ∈ { ℤ × ℤ }
n ∈ ℤ A_ij = | 1 if (i,j) ∈ E
| 0 otherwise
where
A ∈ ℝ^(n × n)
E ∈ { ℤ × ℤ }
n ∈ ℤ