I would like to reference elements of a matrix $A$ such that each element can be found by its corresponding row and column position. Namely, $a_{ij}$ where $i$'s are rows and $j$'s are columns. The issue occurs with large matrices.
For example, a $150 \times 150$ matrix has elements $a_{ij}: 1 \leq i \leq 150,1\leq j \leq 150$.
Let's say I want to evaluate the element at the index $a_{123}$. How can the reader tell if I'm referencing the indices $i=1,j=23$ or $i=12,j=3$?
Is there a convention which solves this issue, or is it up to stylistic choice?