C GERADK    SOURCE    CHAT      05/01/13    00:17:55     5004
      SUBROUTINE GERADK(XEL,GEOM)
C |====================================================================|
C |                                                                    |
C |        CALCULE DES CONSTANTES D UN TRIANGLE POUR L ELEMENT DKT     |
C |                                                                    |
C |==== ENTREES                                                        |
C |        XEL(3,3)= COORDONNEES DE L ELEMENT                          |
C |==== SORTIES                                                        |
C |        GEOM(17)=DES CONSTANTES POUR LE DKT                         |
C |   CODE SUO X.Z.                                                    |
C |====================================================================|
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8(A-H,O-Z)
      DIMENSION XEL(3,*),GEOM(*)
      DATA TRSQUA/0.75D0/,UNQUA/0.25D0/,UNDEMI/0.5D0/
      X12=XEL(1,1)-XEL(1,2)
      X23=XEL(1,2)-XEL(1,3)
      X31=XEL(1,3)-XEL(1,1)
      Y12=XEL(2,1)-XEL(2,2)
      Y23=XEL(2,2)-XEL(2,3)
      Y31=XEL(2,3)-XEL(2,1)
      XSQ12=X12*X12
      XSQ23=X23*X23
      XSQ31=X31*X31
      YSQ12=Y12*Y12
      YSQ23=Y23*Y23
      YSQ31=Y31*Y31
      DIST12=XSQ12+YSQ12
      DIST23=XSQ23+YSQ23
      DIST31=XSQ31+YSQ31
      A4=-X23/DIST23
      A5=-X31/DIST31
      A6=-X12/DIST12
      D4=-Y23/DIST23
      D5=-Y31/DIST31
      D6=-Y12/DIST12
      B4=TRSQUA*X23*Y23/DIST23
      B5=TRSQUA*X31*Y31/DIST31
      B6=TRSQUA*X12*Y12/DIST12
      C4=(UNQUA*XSQ23-UNDEMI*YSQ23)/DIST23
      C5=(UNQUA*XSQ31-UNDEMI*YSQ31)/DIST31
      C6=(UNQUA*XSQ12-UNDEMI*YSQ12)/DIST12
      E4=(UNQUA*YSQ23-UNDEMI*XSQ23)/DIST23
      E5=(UNQUA*YSQ31-UNDEMI*XSQ31)/DIST31
      E6=(UNQUA*YSQ12-UNDEMI*XSQ12)/DIST12
      GEOM(1)=A4
      GEOM(2)=A5
      GEOM(3)=A6
      GEOM(4)=B4
      GEOM(5)=B5
      GEOM(6)=B6
      GEOM(7)=C4
      GEOM(8)=C5
      GEOM(9)=C6
      GEOM(10)=D4
      GEOM(11)=D5
      GEOM(12)=D6
      GEOM(13)=E4
      GEOM(14)=E5
      GEOM(15)=E6
      GEOM(16)=1.D0
      GEOM(17)=1.D0
      RETURN
      END