difflog(EXPR)
difflog(EXPR,K)
If the input argument K
is not specified, this pseudofunction expands to
(log(EXPR)-log(EXPR{-1}))
If the input argument K
is specified, it expands to
(log(EXPR)-log(EXPR{K}))
The two derived expressions, EXPR{-1}
and EXPR{K}
, are based on EXPR
, and have all its time subscripts shifted by --1 or by K
periods, respectively.
The following two lines of code
difflog(Z)
difflog(X{1}/Y{-1},-2)
will expand to
(log(Z)-log(Z{-1}))
(log(X{1}/Y{-1})-log(X{-1}/Y{-3}))