[ABAP] How do I implement and work with multi-dimensional arrays or matrices in ABAP?

In ABAP, multi-dimensional arrays or matrices are implemented using nested internal tables or nested structures. Here's how you can implement and work with multi-dimensional arrays or matrices in ABAP:

1. Define a nested structure: Define a structure that represents an individual element of the array. This structure can contain multiple fields representing different dimensions of the array.

1TYPES: BEGIN OF ty_cell,
2         field1 TYPE data_type1,
3         field2 TYPE data_type2,
4         ...
5       END OF ty_cell.

2. Define a nested internal table: Define an internal table that represents a single dimension of the array. Each entry of this internal table will be an instance of the nested structure defined above.

1TYPES: tt_dimension TYPE TABLE OF ty_cell.

3. Define the multi-dimensional array: Define an internal table that represents the multi-dimensional array. Each entry of this internal table will be an instance of the nested internal table defined above.

1TYPES: tt_array TYPE TABLE OF tt_dimension.
2DATA: it_array TYPE tt_array.

4. Populate and access elements of the array: You can populate the array and access its elements using nested loops.

1DATA: it_dimension TYPE tt_dimension,
2      ls_cell TYPE ty_cell.
3
4LOOP AT it_array INTO it_dimension.
5  LOOP AT it_dimension INTO ls_cell.
6    " Access fields of the nested structure
7    WRITE: / ls_cell-field1, ls_cell-field2.
8  ENDLOOP.
9ENDLOOP.

5. Modify elements of the array: You can modify elements of the array using the MODIFY statement along with appropriate index values.

1DATA(lv_index1) = 1.
2DATA(lv_index2) = 2.
3
4" Modify field1 of the specified element
5MODIFY it_array[ lv_index1 ][ lv_index2 ]-field1 = new_value.

6. Resize the array: You can resize the array by appending or deleting entries from the nested internal tables using the APPEND and DELETE statements.

1DATA(lv_index) = 3.
2
3" Append a new row to the array
4APPEND INITIAL LINE TO it_array.
5
6" Delete a row from the array
7DELETE it_array[ lv_index ].

These are the basic steps to implement and work with multi-dimensional arrays or matrices in ABAP. You can adapt them based on your specific requirements and the complexity of the array structure.