quat_mul - Multiplies two quaternions. Allegro game programming library.

       Multiplies two quaternions, storing the result in out. The resulting quaternion will have the same effect
       as  the  combination  of  p  and  q, ie.  when applied to a point, (point * out) = ((point * p) * q). Any
       number of rotations can be  concatenated  in  this  way.  Note  that  quaternion  multiplication  is  not
       commutative, ie. quat_mul(p, q) != quat_mul(q, p).

Allegro                                           version 4.4.3                                quat_mul(3alleg4)

       quat_mul - Multiplies two quaternions. Allegro game programming library.

#include<allegro.h>voidquat_mul(constQUAT*p,constQUAT*q,QUAT*out);