The necessary functional components and informa- tion flow for instrumenting the cross-addition are asso- ciated with the Y and registers shown in Fig. 2. It has not yet been shown how the prescribed se- quence of rotation steps can be controlled to effect the desired over-all rotation. By examination of (15)and (16), it may be shown that, for a rotation of a set of co- ordinate components Yi and through a given angle (as required in the ROTATION mode), it is necessary to obtain the expressions