C #TRIANG V1A 15-FEB-73. C LAST UPDATE: C FUNCTION TRIANG(J1,J2,J3) C C *PURPOSE. C TO RETURN THE TRIANGLE FUNCTION OF FACTORIALS FOR THE C ANGULAR MOMENTUM QUANTUM NUMBERS "J", OR ZERO IF THESE CANNOT C COUPLE TO ANGULAR MOMENTUM ZERO. C C *PARAMETERS: C J1 - FIRST ANGULAR MOMENTUM QUANTUM NUMBER. C J2 - SECOND C J3 - AND THIRD. C C !!NOTE!! BY CONVENTION ALL ANGULAR MOMENTUM QUANTUM NUMBERS C HAVE TWICE THEIR PHYSICAL VALUES AND ARE INTEGERS!!. C C INPUT PARAMETERS: C J1, J2, J3 C OUTPUT PARAMETERS: C (FUNCTION VALUE ONLY) C C *METHOD. C STRAIGHTFORWARD. C C *ACCURACY. C C *RESTRICTIONS. C C *ERROR CONDITIONS. C C *NON STANDARD ROUTINES CALLED. C FAC2 - FACTORIAL OF HALF ITS ARGUMENT - MRMLIB. C LOGTRI - LOGICAL TEST OF TRIANGLE RELATION FOR C THE J VALUES - MRMLIB. C C *TYPICAL TIMES. C C *ORIGIN. M.R.MANNING. C C *COMMENTS. C C #END. C C #START. LOGICAL LOGTRI TRIANG=0. IF(LOGTRI(J1,J2,J3) ) TRIANG=FAC2(J1+J2-J3)*FAC2(J2+J3-J1) 1 *FAC2(J3+J1-J2)/ FAC2(J1+J2+J3+2) RETURN END