[ADMB Users] operators in ADMB or R got it wrong
otter at otter-rsch.com
Wed Aug 12 09:36:35 PDT 2009
It is often said that if u and v are vectors in ADMB then
should be an element-wise product because it is so in R.
What if M is a matrix? It is useful to have
be the product of a matrix times a vector yielding another vector.
If M and N are both matrices then M*N should be matrix
multiplication. If M represents a quadratic form then
should be the usual number obtained by u * (M *n)
u*M*inv(M)*v should be equal to u * Id *v = u*v
All of this speaks to the fact that u*v should be the dot product and
R got it wrong.
David A. Fournier
P.O. Box 2040,
Sidney, B.C. V8l 3S3
More information about the Users