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MATXRO

       SUBROUTINE  MATXRO (A,B,C, D,E,F)
 C$    (Transform -- Matrix Rotating Point to Point)
 C$    Compute a  matrix  which  takes  a point  that  is  a  unit
 C$    distance along the  vector (A,B,C) from  the origin into  a
 C$    point the  same distance  from the  origin, but  along  the
 C$    vector (D,E,F).
 C$
 C$    The stored transformation matrix is multiplied on the right
 C$    by the computed rotation matrix.
 C$
 C$    The matrix,  T, corresponds  to a  rotation by  some  angle
 C$    about an  axis perpendicular  to  both vectors.   Thus,  if
 C$    (A,B,C) and (D,E,F) are unit vectors, the transformation is
 C$
 C$    (A,B,C,1)T --> (D,E,F,1).
 C$
 C$    If either  of  the  vectors  is (0,0,0),  or  if  they  are
 C$    colinear, then a unit (or -unit) matrix is used.
 C$
 C$    MATXSM() sets  the  stored  matrix  to  a  starting  value,
 C$    MATXIM() inquires the current  value, and MATXIO()  selects
 C$    printing of intermediate matrices.
 C$    (08-FEB-90)