The newly released version 1.33.0 of boost removes operator[]
from the interface of boost::numeric::ublas::matrix_expression.
This operator is used a lot in frontends/CsoundVST.  Instances
of "some_matrix_variable[x][y]" have to be replaced with "some_matrix_variable(x,y)".  I've attached a patch which does
this (apply with "patch -p0 < csound-matrix-patch" in csound5
directory).

I believe this patch will be backwards compatible with earlier
boost versions, since operator[] was just an inline call to
operator() anyway.

Hope it helps,
Russell