Hans,

This typesets (pdf) fine on my system.

\starttext

\subject{Unorthodox}

Subtracting a scalar from a matrix or vector makes no sense
mathematically.
\startformula
\left(\matrix{1 & 2 & 3\cr 4 & 5 & 6}\right)-1
\stopformula
However, this is such a common occurrence, Matlab interprets this to
mean
\startformula
\left(\matrix{1 & 2 & 3\cr 4 & 5 & 6}\right)-1
=\left(\matrix{0 & 1 & 2\cr 3 & 4 & 5}\right).
\stopformula

\stoptext

However, the exact same construct in the attached file doesn't show the
equal sign when viewed in Acrobat. How come?