forceSymmetric {Matrix} | R Documentation |
Force a square matrix x
to a symmetricMatrix
,
without a symmetry check as it would be applied for as(x,
"symmetricMatrix")
.
forceSymmetric(x, uplo)
x |
any square matrix (of numbers), either “"traditional"”
( |
uplo |
optional string, |
a square matrix inheriting from class
symmetricMatrix
.
symmpart
for the symmetric part of a matrix, or
the coercions as(x, <symmetricMatrix class>)
.
## Hilbert matrix
i <- 1:6
h6 <- 1/outer(i - 1L, i, "+")
sd <- sqrt(diag(h6))
hh <- t(h6/sd)/sd # theoretically symmetric
isSymmetric(hh, tol=0) # FALSE; hence
try( as(hh, "symmetricMatrix") ) # fails, but this works fine:
H6 <- forceSymmetric(hh)
## result can be pretty surprising:
(M <- Matrix(1:36, 6))
forceSymmetric(M) # symmetric, hence very different in lower triangle
(tm <- tril(M))
forceSymmetric(tm)