How can a given (4x4) matrix be copied from Maple to MATLAB?
In Maple, you should be able to use the ExportMatrix command to produce a file (from numeric Matrices or Vectors) which Matlab can read.
Maple 15 and later allow for export to a binary file format that Matlab can read. Older versions such a 14, 13, etc could export with that command only to ASCII format files that Matlab could read.