fit3gauss: Fit Gaussians to Three Absorption Features
In rvmethod: Radial Velocity Method for Detecting Exoplanets

Description Usage Arguments Value Examples

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.

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

`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

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

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)