Support for Function alias.lm()
USAGE:
pattern(object, abbreviate.col)
This is support for the function alias.lm(). It takes a numeric vector
or matrix and tries to produce a simple set of values for the nonzero entries.
The heuristic used is to zap all small values, then try to represent the
remaining ones as a (possibly signed) set of as few numbers as reasonable.
The function works fine if there is only essentially one nonzero value,
up to sign. Its success in more complicated cases is hit-or-miss.