c
c _____________________________
c
c
	subroutine comquat(qq,qresult)
	real qq(4,2),qresult(4)
c
c       PI=3.14159265
c
c  algorithm for forming resultant quaternion as Q1 x Q2^-1
c  where Q2 follows Q1, i.e. is the second rotation;
c  note change of signs to get inverse of second orientation
c
	qresult(1)=qq(1,1)*qq(4,2)-qq(4,1)*qq(1,2)
     &	+qq(2,1)*qq(3,2)-qq(3,1)*qq(2,2)
	qresult(2)=qq(2,1)*qq(4,2)-qq(4,1)*qq(2,2)
     &	+qq(3,1)*qq(1,2)-qq(1,1)*qq(3,2)
	qresult(3)=qq(3,1)*qq(4,2)-qq(4,1)*qq(3,2)
     &	+qq(1,1)*qq(2,2)-qq(2,1)*qq(1,2)
	qresult(4)=qq(4,1)*qq(4,2)+qq(1,1)*qq(1,2)
     &	+qq(2,1)*qq(2,2)+qq(3,1)*qq(3,2)
c
c	write(*,*) 'qresult ',qresult
c
	return
	end
c
c _____________________________
c