search for: jointll2

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2011 Sep 22
1
nlm's Hessian update method
...of different ways to do this, and seems to conclude that the positive-definite secant method (BFGS) works best in practice (p201). However, when I run my code through the optim function with the method as "BFGS", slightly different estimates are produced to that of nlm: > optim(strt,jointll2,method="BFGS",hessian=T)$par -0.4016808 0.6057144 0.3744790 -7.1819734 3.0230386 0.4446641 > nlm(jointll2,strt,hessian=T)$estimate [1] -0.4016825 0.6057159 0.3744765 -7.1819737 3.0230386 0.4446623 Can anyone tell me if nlm employs the BFGS method for updati...