This operation updates an matrix *C* by multiplying
symmetric matrix *A* times an matrix *B* :

Here
*L* and indicate
the lower- and strictly lower triangular part of matrix *A* ,
respectively, and
*U* and indicate
the upper- and strictly upper triangular part of matrix *A* , respectively.
Which of these formulae is used is determined by parameters
`SIDE` and `UPLO`.