| Description: |
This function iterates through the given array indices and checks if
they lie inside the specified range [0,height) and [0,width),
respectively.
Indices are modified according to the following rules:
1. If both indices lie inside [0,height) and [0,width), respectively,
they are left untouched.
2. If the row index lies outside [0,height) it is cyclicly wrapped
around. That is, a suitable multiple of "height" is added or
substracted, that makes the index fall inside [0,height).
3. If the column index lies outside [0,width) it is cyclicly wrapped
around. That is, a suitable multiple of "width" is added or
substracted, that makes the index fall inside [0,width).
Thus, the indices are effectively wrapped around the array edges;
that is, they are mapped onto a torus of dimensions height,width.
Note that by NEST convention, for index pairs, the first index denotes
the row, and the second index denotes the column.
Dimensions of the index array are preserved.
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