`tetra` <-
function(u, R, crit=1e-6, maxiter=20)
{
n = length(u);
if (n == 1) { return( list( Sigma=1, fail=0, locFail=c(NA, NA) ) ) }
sigma = R;
for ( i in seq(1,n-1) )
{
for (j in seq(i+1, n) )
{
tcor = tetra1( c(u[i],u[j]), R[i,j] );
if (as.logical(tcor[2]))
{
myList = list( Sigma=sigma, fail=tcor[2], locFail=c(i,j) )
return(myList)
}
else
{
sigma[i,j]=tcor[1] # upper half only, i < j #
}
}
}
myList <- list( Sigma=sigma, fail=tcor[2], locFail=c(NA, NA) )
return(myList)
}