### SLA_MXV

Apply 3D Rotation

ACTION:
Multiply a 3-vector by a rotation matrix (single precision).
CALL:
CALL sla_MXV (RM, VA, VB)
##### GIVEN:
 RM R(3,3) rotation matrix VA R(3) vector to be rotated

##### RETURNED:
 VB R(3) result vector

NOTES:
(1)
This routine performs the operation:

b = M$\cdot$a

where a and b are the 3-vectors VA and VB respectively, and M is the $3×3$ matrix RM.
(2)
The main function of this routine is apply a rotation; under these circumstances, M is a proper real orthogonal matrix.
(3)
To comply with the ANSI Fortran 77 standard, VA and VB must not be the same array. The routine is, in fact, coded so as to work properly with many Fortran compilers even if this rule is violated, something that is not, however, recommended.