Sources Esope | Cast3M

eqpl3p
C EQPL3P    SOURCE    CHAT      05/01/12    23:44:05     5004
      FUNCTION EQPL3P(XX,X1,X2,X3)
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)
C************************************************************************
C
C     Calcule la valeur de l'equation d'un plan passant par 3pts A,B,C
C     au point (x,y,z)
C************************************************************************
      DIMENSION XX(3),X1(3),X2(3),X3(3)
 
      XA=X1(1)
      YA=X1(2)
      ZA=X1(3)
 
      XB=X2(1)
      YB=X2(2)
      ZB=X2(3)
 
      XC=X3(1)
      YC=X3(2)
      ZC=X3(3)
 
      X=XX(1)
      Y=XX(2)
      Z=XX(3)
 
      FX=(YB-YA)*(ZC-ZA)-(ZB-ZA)*(YC-YA)
      FY=(XC-XA)*(ZB-ZA)-(XB-XA)*(ZC-ZA)
      FZ=(XB-XA)*(YC-YA)-(YB-YA)*(XC-XA)
 
      EQPL3P=FX*(X-XA)+FY*(Y-YA)+FZ*(Z-ZA)
      RETURN
      END