Computes the exponential transformation, including its inverse and the first two derivatives.
Numeric or character. See below for further details.
The exponential link function is potentially suitable for parameters that
Numerical values of
theta close to negative or positive infinity
may result in
deriv = 0, the exponential of
inverse = FALSE.
inverse = TRUE then
theta is not positive then it will return
deriv = 1, then the function returns
eta / d
theta as a function of
inverse = FALSE,
inverse = TRUE then it returns the reciprocal.
Here, all logarithms are natural logarithms, i.e., to base e.
This function has particular use for computing quasi-variances when
Numerical instability may occur when
close to negative or positive infinity.
One way of overcoming this (one day) is to use
Thomas W. Yee
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