C FZ2       SOURCE    CHAT      05/01/13    00:14:15     5004           
      FUNCTION FZ2(D,A,U,SQA,SQU,RSINT2)                                        
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)                                                 
      SQAD=SQA**2-D**2                                                          
      SQUD=SQU**2-D**2                                                          
      IF(SQAD.EQ.0.D0) GOTO 2                                                   
1     IF(SQUD.EQ.0.D0) GOTO 3                                                   
      GOTO 4                                                                    
2     FZ2=-SIGN(A,D)                                                            
      RETURN                                                                    
3     FZ2=+SIGN(U,D)                                                            
      RETURN                                                                    
4     FZ2=-D*RSINT2*(A/(SQAD*SQA)-U/(SQUD*SQU))                                 
      RETURN                                                                    
      END