schechter.fit: Fit to the Schechter Function

In astro: Astronomy Functions, Tools and Routines

Description

This function calculates a Schechter function fit to a set of input data.

Usage

schechter.fit(data, vmax = NA, knee, slope, norm, knee.alt = NA, 
              slope.alt = NA, norm.alt = NA, kneelo = -Inf, 
              slopelo = -Inf, normlo = 0, kneehi = Inf, slopehi = Inf, 
              normhi = Inf, fixk1 = FALSE, fixs1 = FALSE, fixn1 = FALSE, 
              fixk2 = FALSE, fixs2 = FALSE, fixn2 = FALSE, 
              range = range(data), lim1 = NA, lim2 = NA, numlim = 1, 
              method = "nlminb", volume = max(vmax), bw = 0.1, 
              mag = FALSE, log = FALSE, null = 1E-9, error = "jack", 
              subvol = 10, sampnum = subvol, msun = solar("r"))

Arguments

data	input data vector
vmax	vector of maximum comoving volumes within which object could lie
knee	the knees(s) of the Schechter function (L_star/M_star)
slope	the slope(s) of the Schechter function (alpha)
norm	the normalisation(s) of the Schechter function (phi_star)
knee.alt	alternative knees(s) of the Schechter function (L_star/M_star)
slope.alt	alternative slope(s) of the Schechter function (alpha)
norm.alt	alternative normalisation(s) of the Schechter function (phi_star)
kneelo	a lower bound on the knee parameter
slopelo	a lower bound on the slope parameter
normlo	a lower bound on the norm parameter
kneehi	an upper bound on the knee parameter
slopehi	an upper bound on the slope parameter
normhi	an upper bound on the norm parameter
fixk1	fix the first knee?
fixs1	fix the first slope?
fixn1	fix the first normalisation?
fixk2	fix the second knee?
fixs2	fix the second slope?
fixn2	fix the second normalisation?
range	data range of interest
lim1	lower data limit for fitting
lim2	upper data limit for fitting
numlim	lower number (per bin) limit for fitting
method	choice of 'nlminb' (recommended) or one of 'optim's minimisation methods (e.g., 'Nelder-Mead')
volume	total volume across which the data has been collected (default 1 if vmax = NA)
bw	bin width sizes
mag	are the input data magnitudes?
log	are the input data logged?
null	value of null
error	parameter error estimation method [jack/boot]
subvol	number of sub-volumes to split the input data into
sampnum	number of samplings to be made for bootstrapping method
msun	absolute magnitude of the sun (to be used in calculation of the luminosity density should mag=TRUE)

Value

binmid	bin midpoints
num	number per bin
den	density per bin
err	error per bin
errlo	lower error limit
errhi	upper error limit
par	best fit parameters
parlo	lower error estimates on recovered fit parameters
parhi	upper error estimates on recovered fit parameters
j	luminosity density
jlo	lower luminosity density limit
jhi	upper luminosity density limit
chi2	chi2 value
dof	number of degrees of freedom
rchi2	reduced chi2
pval	probability of observing chi2 value by chance [significant: pval < 0.05]
denlim	lower density limit used
hessian	optim hessian output

Author(s)

Lee Kelvin <[e-mail]>

References

Blanton M. R., Lupton R. H., Schlegel D. J., Strauss M. A., Brinkmann J., Fukugita M., Loveday J., 2005, ApJ, 631, 208

Driver S. P., Popescu C. C., Tuffs R. J., Graham A. W., Liske J., Baldry I., 2008, ApJ, 678, L101

Baldry I. K. Driver S. P., Loveday J., et al., 2012, MNRAS, 421, 621

See Also

The astronomy package: astro.

astro documentation built on May 2, 2019, 2:14 a.m.