Sources/misc/coefpoly.f


! $Header: /home/cvsroot/LMDZ4/libf/dyn3d/coefpoly.F,v 1.1.1.1 2004/05/19
! 12:53:05 lmdzadmin Exp $

SUBROUTINE coefpoly(xf1, xf2, xprim1, xprim2, xtild1, xtild2, a0, a1, a2, a3)
  IMPLICIT NONE

  ! ...  Auteur :   P. Le Van  ...


  ! Calcul des coefficients a0, a1, a2, a3 du polynome de degre 3 qui
  ! satisfait aux 4 equations  suivantes :

  ! a0 + a1*xtild1 + a2*xtild1*xtild1 + a3*xtild1*xtild1*xtild1 = Xf1
  ! a0 + a1*xtild2 + a2*xtild2*xtild2 + a3*xtild2*xtild2*xtild2 = Xf2
  ! a1  +     2.*a2*xtild1 +     3.*a3*xtild1*xtild1 = Xprim1
  ! a1  +     2.*a2*xtild2 +     3.*a3*xtild2*xtild2 = Xprim2

  ! On en revient a resoudre un systeme de 4 equat.a 4 inconnues a0,a1,a2,a3

  DOUBLE PRECISION xf1, xf2, xprim1, xprim2, xtild1, xtild2, xi
  DOUBLE PRECISION xfout, xprim
  DOUBLE PRECISION a1, a2, a3, a0, xtil1car, xtil2car, derr, x1x2car

  xtil1car = xtild1*xtild1
  xtil2car = xtild2*xtild2

  derr = 2.*(xf2-xf1)/(xtild1-xtild2)

  x1x2car = (xtild1-xtild2)*(xtild1-xtild2)

  a3 = (derr+xprim1+xprim2)/x1x2car
  a2 = (xprim1-xprim2+3.*a3*(xtil2car-xtil1car))/(2.*(xtild1-xtild2))

  a1 = xprim1 - 3.*a3*xtil1car - 2.*a2*xtild1
  a0 = xf1 - a3*xtild1*xtil1car - a2*xtil1car - a1*xtild1

  RETURN
END SUBROUTINE coefpoly
1	guez	3
2	guez	81	! $Header: /home/cvsroot/LMDZ4/libf/dyn3d/coefpoly.F,v 1.1.1.1 2004/05/19
3			! 12:53:05 lmdzadmin Exp $
4	guez	3
5	guez	81	SUBROUTINE coefpoly(xf1, xf2, xprim1, xprim2, xtild1, xtild2, a0, a1, a2, a3)
6			IMPLICIT NONE
7	guez	3
8	guez	81	! ... Auteur : P. Le Van ...
9	guez	3
10
11	guez	81	! Calcul des coefficients a0, a1, a2, a3 du polynome de degre 3 qui
12			! satisfait aux 4 equations suivantes :
13	guez	3
14	guez	81	! a0 + a1xtild1 + a2xtild1xtild1 + a3xtild1xtild1xtild1 = Xf1
15			! a0 + a1xtild2 + a2xtild2xtild2 + a3xtild2xtild2xtild2 = Xf2
16			! a1 + 2.a2xtild1 + 3.a3xtild1*xtild1 = Xprim1
17			! a1 + 2.a2xtild2 + 3.a3xtild2*xtild2 = Xprim2
18	guez	3
19	guez	81	! On en revient a resoudre un systeme de 4 equat.a 4 inconnues a0,a1,a2,a3
20	guez	3
21	guez	81	DOUBLE PRECISION xf1, xf2, xprim1, xprim2, xtild1, xtild2, xi
22			DOUBLE PRECISION xfout, xprim
23			DOUBLE PRECISION a1, a2, a3, a0, xtil1car, xtil2car, derr, x1x2car
24	guez	3
25	guez	81	xtil1car = xtild1*xtild1
26			xtil2car = xtild2*xtild2
27
28			derr = 2.*(xf2-xf1)/(xtild1-xtild2)
29
30			x1x2car = (xtild1-xtild2)*(xtild1-xtild2)
31
32			a3 = (derr+xprim1+xprim2)/x1x2car
33			a2 = (xprim1-xprim2+3.a3(xtil2car-xtil1car))/(2.*(xtild1-xtild2))
34
35			a1 = xprim1 - 3.a3xtil1car - 2.a2xtild1
36			a0 = xf1 - a3xtild1xtil1car - a2xtil1car - a1xtild1
37
38			RETURN
39			END SUBROUTINE coefpoly