C TRACTI    SOURCE    CHAT      05/01/13    03:44:22     5004           
      SUBROUTINE TRACTI (RESU,EPST,SIG,EPS,NCOURB,ICLE,IBI)                     
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8(A-H,O-Z)                                                  
      DIMENSION SIG(*),EPS(*)                                                   
C                                                                               
C  ICLE = 1  ON CALCULE LA PENTE A LA COURBE DE TRACTION                        
C  ICLE = 2  ON CALCULE LA CONTRAINTE                                           
C  IBI NON NUL  : ERREUR : ON DEPASSE LE BOUT DE LA COURBE

C                                                                               
C                ON INTERPOLE LINEAIREMENT                                      
C                                                                               
      IBI=0
*
*    TEST POUR VOIR SI ON DEPASSE EN EPSILON
*
      IF(EPST.GT.1.1D0*EPS(NCOURB)) THEN
         IBI=1
         RETURN
      ENDIF
*
      DO 11 I=2,NCOURB                                                          
      IP=I                                                                      
      IF(EPS(I).GT.EPST) GO TO 13                                               
  11  CONTINUE                                                                  
  13  CONTINUE                                                                  
      IP1=IP-1                                                                  
      PENTE=(SIG(IP)-SIG(IP1))/(EPS(IP)-EPS(IP1))                               
      GO TO (1,2),ICLE                                                          
1     RESU=PENTE                                                                
      RETURN                                                                    
2     RESU=SIG(IP1)+PENTE*(EPST-EPS(IP1))                                       
      RETURN                                                                    
      END