added further matrix exponential tests

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18503 8618b1d8-e22c-0410-b026-96a5dba3e089
added further matrix exponential tests

git-svn-id: svn://svn.code.sf.net/p/quantlib/code/trunk/QuantLib@18504 8618b1d8-e22c-0410-b026-96a5dba3e089