Eckerle4 {NISTnls} | R Documentation |
The Eckerle4
data frame has 35 rows and 2 columns giving
transmittance as a function of wavelength.
This data frame contains the following columns:
These data are the result of a NIST study involving circular interference transmittance. The response variable is transmittance, and the predictor variable is wavelength.
Eckerle, K., NIST (197?). Circular Interference Transmittance Study.
Try <- function(expr) if (!inherits(val <- try(expr), "try-error")) val plot(y ~ x, data = Eckerle4) ## should fail - ridiculous starting value for b3 Try(fm1 <- nls(y ~ (b1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, start = c(b1 = 1, b2 = 10, b3 = 500))) Try(fm1a <- nls(y ~ (b1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, alg = "port", start = c(b1 = 1, b2 = 10, b3 = 500))) Try(fm2 <- nls(y ~ (b1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, start = c(b1 = 1.5, b2 = 5, b3 = 450))) Try(fm2a <- nls(y ~ (b1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, alg = "port", start = c(b1 = 1.5, b2 = 5, b3 = 450))) ## should fail - ridiculous starting value for b3 Try(fm3 <- nls(y ~ (1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, start = c(b2 = 10, b3 = 500), algorithm = "plinear")) Try(fm4 <- nls(y ~ (1/b2) * exp(-0.5*((x-b3)/b2)**2), Eckerle4, trace = TRUE, start = c(b2 = 5, b3 = 450), algorithm = "plinear"))