MGH17 {NISTnls} | R Documentation |
The MGH17
data frame has 33 rows and 2 columns
This data frame contains the following columns:
This problem was found to be difficult for some very good algorithms.
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.
Osborne, M. R. (1972). Some aspects of nonlinear least squares calculations. In Numerical Methods for Nonlinear Optimization, Lootsma (Ed). New York, NY: Academic Press, pp. 171-189.
Try <- function(expr) if (!inherits(val <- try(expr), "try-error")) val plot(y ~ x, data = MGH17) ## Starting values here are ridiculous Try(fm1 <- nls(y ~ b1 + b2*exp(-x*b4) + b3*exp(-x*b5), data = MGH17, trace = TRUE, start = c(b1 = 50, b2 = 150, b3 = -100, b4 = 1, b5 = 2))) Try(fm1a <- nls(y ~ b1 + b2*exp(-x*b4) + b3*exp(-x*b5), data = MGH17, trace = TRUE, alg = "port", start = c(b1 = 50, b2 = 150, b3 = -100, b4 = 1, b5 = 2))) Try(fm2 <- nls(y ~ b1 + b2*exp(-x*b4) + b3*exp(-x*b5), data = MGH17, trace = TRUE, start = c(b1 = 0.5, b2 = 1.5, b3 = -1, b4 = 0.01, b5 = 0.02))) Try(fm2a <- nls(y ~ b1 + b2*exp(-x*b4) + b3*exp(-x*b5), data = MGH17, trace = TRUE, alg = "port", start = c(b1 = 0.5, b2 = 1.5, b3 = -1, b4 = 0.01, b5 = 0.02))) Try(fm3 <- nls(y ~ cbind(1, exp(-x*b4), exp(-x*b5)), data = MGH17, trace = TRUE, algorithm = "plinear", start = c(b4 = 1, b5 = 2))) Try(fm4 <- nls(y ~ cbind(1, exp(-x*b4), exp(-x*b5)), data = MGH17, trace = TRUE, algorithm = "plinear", start = c(b4 = 0.01, b5 = 0.02)))