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Published on *OpenMx* (http://openmx.ssri.psu.edu)

wiki home [1]: operators and functions [2]

The quadratic product "%&%" is a convenient (and efficient) function for pre- and post-multiplying a matrix **B** by another matrix **A** and its transpose **A**', ie.. **A*****B*****A**'

Quadratic form has several uses (see Quadratic form (statistics) [3]

**A** %&% **B** is equivalent to **A** %*% **B** %*% t(**A**)

Conformability is cA=rB=cB

**Links**

[1] http://openmx.psyc.virginia.edu/wiki/main-page

[2] http://openmx.psyc.virginia.edu/wiki/matrix-operators-and-functions

[3] http://en.wikipedia.org/wiki/Quadratic_form_(statistics)