sfaExpand for the default
expansion function.sfa2Create(ppRange, sfaRange, ppType = "SFA1",
axType = "ORD1", regCt = 0, opts = NULL,
xpDimFun = xpDim, sfaExpandFun = sfaExpand)sfaTimediffsfaList contains all arguments passed into
sfa2create plusxpDimFun(ppRange)sfa2 sfaStep
sfa1Create