      FUNCTION  FACTMM(M)                                                       
CCC           FACTORIAL   -   (M+M)!/M!                                         
CCC                                                                  
      IMPLICIT  REAL*8(A-H,O-Z)                                                 
      FACTMM= 1.D0                                                              
       IF(M.GE.1)  THEN                                                         
      DO 10 I=1, M                                                              
   10 FACTMM= FACTMM*DFLOAT(I+M)                                                
       END IF                                                                   
      RETURN                                                                    
      END                                                                       
