numOSL (version 1.0)

decompc: Decomposition decay curve (with constant subtracted) in OSL dating

Description

Decomposing the OSL decay curve (type "CW" or "LM") to a specified number of components plus a constant.

Usage

decompc(Sigdata, ncomp = 3, typ = c("cw", "lm"), 
        control.args = list(), transf = FALSE, 
        LEDpower = 60, LEDwavelength = 470, plot = TRUE, 
        xlog = TRUE, lwd = 3, samplename = NULL, outfile = NULL)

Arguments

Sigdata

data.frame(required): two columns, time (t1,t2,etc) and correspond signal values (s1,s2,etc) to be decomposed

ncomp

numeric(with default): the number of components to be decomposed, which must be an integer in the range [1,7]

typ

character(with default): type ("cw" or "lm") of the OSL decay curve, default typ="cw"

control.args

list(with default): further arguments used in differential evolution algorithm, see function decomp

transf

logical(with default): whether transform estimated parameters or not, see details

LEDpower

numeric(with default): LED power (mW/cm2) used for intensity ramping during the measurement

LEDwavelength

numeric(with default): LED wavelength (nm) used for stimulation during the measurement

plot

logical(with default): whether plot the fitted results or not

xlog

logical(with default): tansform x-axis to log-scale for plotting or not

lwd

numeric(with default): the width of curves for plotting

samplename

character(optional): name of the sample

outfile

character(optional): if specified, decomposed signal values will be written to a file of name outfile in .csv format and saved to the current work directory

Value

• Return an invisible list containing following elements:
• Comp.Signal
  fitted values for observations and each component
• pars
  estimated parameters and associated standard errors
• constant
  estimated constant
• value
  sum of square of residual errors
• errorflag
  error message generated during the calculation, if parameters' standard errors can be estimated, errorflag=0, else 1

Details

Function decompc() is used to decompose decay curves with a subtracted constant. For CW-OSL decay curves: I(t)=a1*exp(-b1*t)+a2*exp(-b2*t)+...+ak*exp(-bk*t)+c , k=1, 2, ..., 7, And for LM-OSL decay curves: I(t)=a1*(t/P)*exp(-b1*t^2/(2*P))+a2*(t/P)*exp(-b2*t^2/(2*P))+...+ ak*(t/P)*exp(-bk*t^2/(2*P))+c*(t/P) , k=1, 2, ..., 7 For more details, see function decomp.

See Also

decomp; fastED

Examples

data(Signaldata)
  decompc(Signaldata$cw[,c(1,2)],ncomp=2,typ="cw")
  print(decompc(Signaldata$lm,ncomp=4,typ="lm"))
  res<-decompc(Signaldata$lm1,ncomp=5,typ="lm",transf=TRUE)
  res$pars