On Thu, 26 Sep 2019, Allin Cottrell wrote:
 The flatten() function for arrays of matrices or strings has a
couple
 of enhancements in git.
 Matrices: complex matrices are now handled correctly (but an array
 containing a mixture of complex and real matrices is not accepted). 
Actually, scratch that last bit. We now support mixed matrix types
(treating a real matrix as a complex matrix with zero imaginary part).
That goes for the concatenation operators '~' and '|' too.
Allin