**ACTION:**- Multiply a 3-vector by the inverse of a rotation
matrix (single precision).
**CALL:**`CALL sla_IMXV (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:

where**b**=**M****a****a**and**b**are the 3-vectors VA and VB respectively, and**M**is the matrix RM. - 2.
- The main function of this routine is apply an inverse
rotation; under these circumstances, is
*orthogonal*, with its inverse the same as its transpose. - 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 on the VAX and many other systems even if this rule is violated, something that is**not**, however, recommended.

Starlink User Note 67

P. T. Wallace

12 October 1999

E-mail:ptw@star.rl.ac.uk