rvmethod (version 0.1.2)

fit3gauss: Fit Gaussians to Three Absorption Features

Description

This function takes a spectrum and the wavelength bounds of three neighboring absorption features and uses the functions gauss1func, gauss2func, and/or gauss3func to fit Gaussians to them simultaneously. The final fit is the first of the following five outcomes for which the nonlinear regression algorithm converges: (i) all three Gaussians, (ii) the left two Gaussians, (iii) the right two Gaussians, (iv) just the middle Gaussian, (v) the middle Gaussian with an amplitude of 0. Only the fit parameters for the middle Gaussian are returned.

Usage

fit3gauss(wvl, flx, bnds0, bnds1, bnds2)

Arguments

wvl

the vector of wavelengths of the spectrum to fit to

flx

the vector of normalized flux of the spectrum to fit to

bnds0

a vector of length 2 with the lower and upper bounds of the left absorption feature

bnds1

a vector of length 2 with the lower and upper bounds of the middle absorption feature

bnds2

a vector of length 2 with the lower and upper bounds of the right absorption feature

Value

a list with three components:

mu

the fitted value of the center parameter for the middle Gaussian

sig

the fitted value of the spread parameter for the middle Gaussian

amp

the fitted value of the amplitude parameter for the middle Gaussian

Examples

# NOT RUN {
x = seq(5000, 5003, length.out=200)
y = gauss3func(x, 0.3, 0.5, 0.4, 5001.5, 5002, 5000.4, 0.1, 0.1, 0.13)
y = rnorm(200, mean=y, sd=0.01)
plot(x, y)
abline(v=c(5000.8, 5001.2, 5001.75, 5002.3))
pars = fit3gauss(x, y, c(5000, 5000.8), c(5001.2, 5001.75), c(5001.75, 5002.3))
fitted = gauss1func(x, pars$amp, pars$mu, pars$sig)
lines(x, fitted, col=2)

# }