MGH09 {NISTnls} | R Documentation |
The MGH09
data frame has 11 rows and 2 columns giving
y |
A numeric vector of response values. |
x |
A numeric vector of input values. |
This data frame contains the following columns:
This problem was found to be difficult for some very good algorithms. There is a local minimum at (+inf, -14.07..., -inf, -inf) with final sum of squares 0.00102734....
See More, J. J., Garbow, B. S., and Hillstrom, K. E. (1981). Testing unconstrained optimization software. ACM Transactions on Mathematical Software. 7(1): pp. 17-41.
Kowalik, J.S., and M. R. Osborne, (1978). Methods for Unconstrained Optimization Problems. New York, NY: Elsevier North-Holland.
library(NISTnls) data(MGH09) plot(y ~ x, data = MGH09) ## starting values for this attempt are ridiculous fm1 <- nls(y ~ b1*(x**2+x*b2) / (x**2+x*b3+b4), data = MGH09, trace = TRUE, start = c(b1 = 25, b2 = 39, b3 = 41.5, b4 = 39)) fm2 <- nls(y ~ b1*(x**2+x*b2) / (x**2+x*b3+b4), data = MGH09, trace = TRUE, start = c(b1 = 0.25, b2 = 0.39, b3 = 0.415, b4 = 0.39)) fm3 <- nls(y ~ cbind(x, x**2) / (x**2+x*b3+b4), data = MGH09, trace = TRUE, algorithm = "plinear", start = c(b3 = 41.5, b4 = 39)) fm4 <- nls(y ~ cbind(x, x**2) / (x**2+x*b3+b4), data = MGH09, trace = TRUE, algorithm = "plinear", start = c(b3 = 0.415, b4 = 0.39))