## Saturday, July 21, 2012

### Grid dimensions

The dimensions of a grid are mutable, but the area of the grid is not. As such, in my computer algebra system the dimensions relation is implemented as a place:
(setf [dimensions [[1 2 3] [4 5 6]]] [3 2])

The transpose operation on matrices can be implemented as an automorphism that rearranges the elements of the collection and that reverses the dimensions of the grid.
(zap reverse [dimensions coll])

Any permutation operation, including reverse, can be applied to the dimensions place without every producing an error because permutations do not change the area part of the underlying grid structure.