align_arun: Rigin alignment with Arun algorithm
In conmolfields: Continuous molecular fields

Rigin alignment with Arun algorithm

1	align_arun(p_i, p1_i)

`p_i`
`p1_i`

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (p_i, p1_i) 
{
    p <- rowMeans(p_i)
    p1 <- rowMeans(p1_i)
    q_i <- p_i - p
    q1_i <- p1_i - p1
    H <- q_i %*% t(q1_i)
    s <- svd(H)
    U <- s$u
    V <- s$v
    X <- V %*% t(U)
    detx <- det(X)
    R <- X
    T <- p1 - R %*% p
    list(R = R, T = T, detx = detx)
  }