ordinary vector. Default value of c(-1,1)
corresponds to the usual northeast direction
break.vec
break vector. Default of c(1,0) corresponds to the
usual south direction
start.point
Starting position for the method (ie coordinates of
unity). Default value of NULL corresponds to row 1, column m.
References
Written up in loads of places. The method (at least with
the default ordinary and break vectors) seems to have been known since
at least the Renaissance.
Benson and Jacoby, and the Mathematica website, discuss the problem
with nondefault ordinary and break vectors.