omxGetRAMDepth {OpenMx} | R Documentation |
Get the potency of a matrix for inversion speed-up
omxGetRAMDepth(A, maxdepth = nrow(A) - 1)
A |
MxMatrix object |
maxdepth |
Numeric. maximum depth to check |
This function is used internally by the mxExpectationRAM function
to determine how far to expand (I-A)^{-1} = I + A + A^2 + A^3 + ...
. It is
similarly used by mxExpectationLISREL in expanding (I-B)^{-1} = I + B + B^2 + B^3 + ...
.
In many situations A^2
is a zero matrix (nilpotent of order 2). So when A
has large
dimension it is much faster to compute I+A
than (I-A)^{-1}
.