Purpose
The conditional expressions
use either the
if_true
or if_false
.
Hence, some terms only need to be evaluated
depending on the value of the comparison in the conditional expression.
The optimize
option is capable of detecting some of these
case and determining variables that can be skipped.
This routine returns the number such variables.
n
The return value
n
has type size_t
is the number of variables that the optimizer has determined can be skipped
(given the independent variable values specified by the previous call to
f.Forward
for order zero).