Fit a Linear Mixed Effects Model
DESCRIPTION:
This function is generic; methods functions can be written to handle specific classes of objects. Classes which already have methods for this function include formula and lmList.
USAGE: 
lme(fixed, random = fixed, cluster, data=sys.parent(),
    start = list(D = NULL, theta = NULL, alpha = NULL, delta = NULL),
    est.method=c("RML", "ML"), re.block, re.structure =
    c("unstructured", "diagonal", "identity", "compsymm", "ar1"),
    re.paramtr = c("matrixlog", "cholesky", "spherical",
    "logcholesky", "givens"), serial.structure = c("identity", "ar1",
    "ar1.continuous", "compsymm", "ar2", "ma1", "ma2", ,
    serial.covariate = NULL,
    serial.covariate.transformation = c("rank.within.cluster", "none",
    "round", "global.rank"), var.function = c("identity", "power",
    "expon", "cte.power"), var.covariate = NULL, var.estimate = T,
    na.action, control)
REQUIRED ARGUMENTS:
fixed:
either a linear formula specifying the fixed effects part of the model, or an object inheriting from class lmList.
OPTIONAL ARGUMENTS:
others:
see the documentation on lme.formula.
VALUE:
an object of class lme representing the fit. Generic functions such as print, plot and summary have methods to show the results of the fit. See lme.object for the components of the fit. The functions residuals, coefficients and fitted.values can be used to extract some of its components.
SEE ALSO:
lme.formula , lme.lmList , lme.object .
EXAMPLES: 
See the helpfiles for lme.formula and lme.lmList.