( X ),  if UPLO = 'U',
     T = tril( X ) - (1/2)*diag( X ),  if UPLO = 'L',

  where triu, tril, and diag denote the upper triangular part, lower
  triangular part, and diagonal part of X, respectively. Then,

     op( A )*X*op( A )' = B + B',

  where B := op( A )*T*op( A )'. Matrix B is not symmetric, but it
  can be written as tri( B ) + stri( B ), where tri denotes the
  triangular part specified by UPLO, and stri denotes the remaining
  strictly triangular part. Let R = V + V', with V defined as T
  a