C SIGELP    SOURCE    CHAT      05/01/13    03:16:35     5004           
      SUBROUTINE SIGELP(SIGMA,DSIGMA,SIGEL,DSIGP,STOT,STEST,ITYPE,              
     1   SEL,SPLA,IBOU,S0,SELAS,XMAT,COVNMS,ALFAH,IMAPLA,SSTAR)                 
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8(A-H,O-Z)                                                  
      DIMENSION SIGMA(*),DSIGMA(*),STOT(*),SIGEL(*),DSIGP(*)                    
     1,XMAT(*),COVNMS(*)                                                        
      DATA UN/1.0D0/,ZERO/0.0D0/                                                
C                                                                               
CCCCCCCCCCCCCCC CALCUL DE L INTERSECTION AVEC LE CONVEXE                        
C                                                                               
      CALL ZDANUL(SIGEL,6)                                                      
      CALL ZDANUL(DSIGP,6)                                                      
      AA=VONMIS(DSIGMA,ITYPE,ALFAH,COVNMS)                                      
      BB=VNMS12(DSIGMA,SIGMA,ITYPE,ALFAH,COVNMS)                                
      AA=AA*AA                                                                  
      AA1=AA                                                                    
      BB1=BB                                                                    
      TST=STEST*STEST                                                           
      IF(IMAPLA.EQ.11) GO TO 20                                                 
      C=S0*S0                                                                   
      CC=C-SELAS*SELAS                                                          
      IF(IMAPLA.NE.5) GO TO 11                                                  
C                                                                               
CCCCCCCCCCCCCC   CAS DRUCKER PRAGER                                             
C                                                                               
      EE=TRACE(DSIGMA)                                                          
      FF=TRACE(SIGMA)                                                           
      XMAT22=XMAT(2)*XMAT(2)                                                    
      XMAT11=XMAT(1)*XMAT(1)                                                    
      XMAT13=XMAT(1)*SELAS                                                      
      AA=AA*XMAT22-EE*EE*XMAT11                                                 
      BB=BB*XMAT22-EE*FF*XMAT11+XMAT13*EE                                       
      GO TO 11                                                                  
  20  CONTINUE                                                                  
C                                                                               
CCCCCCCCCCCCAS CHEN ET CHEN                                                     
C                                                                               
      IN=0                                                                      
  90  CONTINUE                                                                  
      IF (IN.EQ.0) GO TO 120                                                    
      AAA=AA                                                                    
      BBB=BB                                                                    
      CCC=CC                                                                    
      DDD=DD                                                                    
      BB=BB1                                                                    
      AA=AA1                                                                    
 120  CONTINUE                                                                  
      DINV1=TRACE(DSIGMA)                                                       
      AA=AA/3+IN*DINV1*DINV1/6                                                  
      CC=VONMIS(SIGMA,ITYPE,ALFAH,COVNMS)                                       
      DINVO=TRACE(SIGMA)                                                        
      CC=CC*CC/3+IN*DINVO*DINVO/6+XMAT(2)*DINVO/3                               
      CC=CC+(-UN+XMAT(1)*DINVO/3)*SELAS*SELAS                                   
      BB=BB*2/3+IN*DINV1*DINVO/3+DINV1*XMAT(2)/3                                
      BB=BB+XMAT(1)*SELAS*SELAS*DINV1/3                                         
      BB=BB/2                                                                   
CCCCC                                                                           
   11 CONTINUE                                                                  
      IF(ABS(AA).GT.TST) GO TO 1                                                
C                                                                               
CCCCCCCCCC  AA EST NUL UNE SEULE SOLUTION                                       
C                                                                               
      IF(ABS(BB).GT.TST) GO TO 10                                               
C                                                                               
CCCCCCCCCC   BB EST NUL <=> DSIGMA=0 SIGMA0=STOT                                
C                                                                               
  110 CONTINUE                                                                  
      XX=SELAS/(S0+1.E-20)                                                      
      CALL AEQBX(SIGEL,SIGMA,XX,IBOU)                                           
      CALL AEQBPC(DSIGP,SIGMA,SIGEL,UN,-UN,IBOU)                                
      SEL=0.                                                                    
      SPLA=1.                                                                   
      GO TO 555                                                                 
  10  CONTINUE                                                                  
C                                                                               
CCCCCCCCCCCCCCAS BB NON NUL                                                     
C                                                                               
      SEL=CC/(2.*BB)                                                            
      GO TO 333                                                                 
  333 CALL AEQBPC(SIGEL,SIGMA,DSIGMA,UN,SEL,IBOU)                               
      SPLA=1.-SEL                                                               
      CALL AEQBX(DSIGP,DSIGMA,SPLA,IBOU)                                        
      GO TO 555                                                                 
    1 CONTINUE                                                                  
C                                                                               
CCCCCCCCCCCCCC  AA NON NUL ON A 2 SOLUTIONS                                     
C                                                                               
      IF(ABS(CC).GT.TST) GO TO 2                                                
C                                                                               
CCCCCCCCCCCCCC 1 SEULE SOLUTION CC NUL                                          
C                                                                               
      SEL=0.                                                                    
      GO TO 333                                                                 
   2  CONTINUE                                                                  
C                                                                               
CCCCCCCCCCCC   2 SOLUTIONS                                                      
C                                                                               
      DD=4.*BB*BB-4.*AA*CC                                                      
      B=2.*BB                                                                   
      IF(AA*CC.GT.0.) GO TO 3                                                   
C                                                                               
CCCC          CC EST NEGATIF ON A 2 SOLUTIONS 1 NEGATIVE 1 POSITIVE             
C      LA BONNE EST LA POSITIVE                                                 
C                                                                               
      SEL=(-B+SQRT(DD))/(2.*AA)                                                 
      GO TO 333                                                                 
    3 CONTINUE                                                                  
C                                                                               
CCCCCCCC    ON A 2 SOLUTIONS POSITIVES OU NEGATIVES                             
C                                                                               
      IF(DD.GT.0.) GO TO 5                                                      
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC                     
CCCCCCCCCCCCC LA DROITE S0 STOT NE COUPE PAS LE CONVEXE   C                     
C              ON CHERCHE LE POINT DU CONVEXE LE          C                     
CCC             PLUS PRES DE STOT ON L APPELLE SIGEL      C                     
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC                     
  130 CONTINUE                                                                  
      XX=SELAS/(SSTAR+1.E-20)                                                   
      CALL AEQBX(SIGEL,STOT,XX,IBOU)                                            
      SEL=0.                                                                    
      SPLA=1.                                                                   
      CALL AEQBPC(DSIGP,STOT,SIGEL,UN,-UN,IBOU)                                 
      GO TO 555                                                                 
    5 CONTINUE                                                                  
C                                                                               
CCCCCCCCCCCCCCCCCCC   ON A 2 SOLUTIONS POSITIVES OU NEGATIVES                   
C                                                                               
      SEL=(-B+SQRT(DD))/(2.*AA)                                                 
      GO TO 333                                                                 
 555  CONTINUE                                                                  
      IF(IMAPLA.NE.11.OR.IN.EQ.1) GO TO 666                                     
      IF(IN.EQ.0) GO TO 80                                                      
      IF(ABS(SELMIN).GE.ABS(SEL)) GO TO 666                                     
      SEL=SELMIN                                                                
      IF(ABS(AAA).LT.TST.AND.ABS(BBB).LT.TST) GO TO 110                         
      IF(ABS(AAA).GT.TST.AND.ABS(CCC).GT.TST.AND.(AAA*CCC).GT.ZERO.             
     .   AND.DDD.LT.ZERO) GO TO 130                                             
      IN=1                                                                      
      GO TO 333                                                                 
  80  SELMIN=SEL                                                                
      IN=-1                                                                     
      GO TO 90                                                                  
 666  CONTINUE                                                                  
      RETURN                                                                    
      END