An alternative strategy suggested by Parks [49] is to generate solutions according to the formula:
where 
is now a
vector of random numbers in the range 
and 
is a diagonal matrix
which defines the maximum change allowed in each variable. After a
successful trial, i.e. after an accepted change in the solution,
is updated:
where 
and 
perform similar roles and 
is a
diagonal matrix the elements of which consist of the magnitudes of
the successful changes made to each control variable. This tunes the
maximum step size associated with each control variable towards a
value giving acceptable changes.
