class PDF::Reader::TransformationMatrix

co-ordinate systems in PDF files are specified using a 3x3 matrix that looks something like this:

[ a b 0 ]
[ c d 0 ]
[ e f 1 ]

Because the final column never changes, we can represent each matrix using only 6 numbers. This is important to save CPU time, memory and GC pressure caused by allocating too many unnecessary objects.