readFullMat(file, ...)
readStackVec(file, ...)
readLowTriMat(file, no.var, ...)

## Not run: 
## Write two full correlation matrices into a file named "fullmat.dat".
## x2 is missing in the second matrix.
## The content of "fullmat.dat" is
# 1.0 0.3 0.4
# 0.3 1.0 0.5
# 0.4 0.5 1.0
# 1.0 NA 0.4
# NA NA NA
# 0.4 NA 1.0

## cat("1.0 0.3 0.4\n0.3 1.0 0.5\n0.4 0.5 1.0
## 1.0 NA 0.4\nNA NA NA\n0.4 NA 1.0",
## file="fullmat.dat", sep="")

## Read the correlation matrices
## my.full <- readFullMat("fullmat.dat")

## my.full
# $`1`
#     x1  x2  x3
# x1 1.0 0.3 0.4
# x2 0.3 1.0 0.5
# x3 0.4 0.5 1.0
#
# $`2`
#     x1 x2  x3
# x1 1.0 NA 0.4
# x2  NA NA  NA
# x3 0.4 NA 1.0

## Write two lower triangle correlation matrices into a file named "lowertriangle.dat".
## x2 is missing in the second matrix.
## The content of "lowertriangle.dat" is
# 1.0 
# 0.3 1.0 
# 0.4 0.5 1.0
# 1.0
# NA NA 
# 0.4 NA 1.0
## cat("1.0\n0.3 1.0\n0.4 0.5 1.0\n1.0\nNA NA\n0.4 NA 1.0",
##     file="lowertriangle.dat", sep="")

## Read the lower triangle correlation matrices
## my.lowertri <- readLowTriMat(file = "lowertriangle.dat", no.var = 3)

## my.lowertri
# $`1`
#     x1  x2  x3
# x1 1.0 0.3 0.4
# x2 0.3 1.0 0.5
# x3 0.4 0.5 1.0
#
# $`2`
#     x1 x2  x3
# x1 1.0 NA 0.4
# x2  NA NA  NA
# x3 0.4 NA 1.0

## Write two vectors of correlation coefficients based on
##  column major into a file named "stackvec.dat".
## x2 is missing in the second matrix.
## The content of "stackvec.dat" is
# 1.0 0.3 0.4 1.0 0.5 1.0
# 1.0 NA 0.4 NA NA 1.0
## cat("1.0 0.3 0.4 1.0 0.5 1.0\n1.0 NA 0.4 NA NA 1.0\n",
##     file="stackvec.dat", sep="")

## my.vec <- readStackVec("stackvec.dat")

## my.vec
# $`1`
#     x1  x2  x3
# x1 1.0 0.3 0.4
# x2 0.3 1.0 0.5
# x3 0.4 0.5 1.0
#
# $`2`
#    x1 x2  x3
# x1 1.0 NA 0.4
# x2  NA NA  NA
# x3 0.4 NA 1.0

## End(Not run)