--- trunk/dyn3d/coefpoly.f	2014/03/26 17:18:58	91
+++ trunk/Sources/dyn3d/coefpoly.f	2015/06/16 17:27:33	146
@@ -1,37 +1,42 @@
+module coefpoly_m
 
-! $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  ...
+contains
+
+  SUBROUTINE coefpoly(y1, y2, yp1, yp2, x1, x2, a0, a1, a2, a3)
+
+    ! From LMDZ4/libf/dyn3d/coefpoly.F, version 1.1.1.1 2004/05/19 12:53:05
 
+    ! Author: P. Le Van
 
-  ! Calcul des coefficients a0, a1, a2, a3 du polynome de degre 3 qui
-  ! satisfait aux 4 equations  suivantes :
+    ! Calcul des coefficients a0, a1, a2, a3 du polynôme de degré 3
+    ! qui passe par les points (x1, Y1) et (x2, Y2) avec les
+    ! dérivées yp1 et yp2. Système linéaire de 4 équations à 4
+    ! inconnues :
 
-  ! 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
+    ! a0 + a1 * x1 + a2 * x1**2 + a3 * x1**3 = Y1
+    ! a0 + a1 * x2 + a2 * x2**2 + a3 * x2**3 = Y2
+    ! a1 + 2 * a2 * x1 + 3 * a3 * x1**2 = Yp1
+    ! a1 + 2 * a2 * x2 + 3 * a3 * x2**2 = Yp2
 
-  ! On en revient a resoudre un systeme de 4 equat.a 4 inconnues a0,a1,a2,a3
+    DOUBLE PRECISION, intent(in):: y1, y2, yp1, yp2, x1, x2
+    DOUBLE PRECISION, intent(out):: a0, a1, a2, a3
 
-  DOUBLE PRECISION xf1, xf2, xprim1, xprim2, xtild1, xtild2
-  DOUBLE PRECISION a1, a2, a3, a0, xtil1car, xtil2car, derr, x1x2car
+    ! Local:
+    DOUBLE PRECISION x1car, x2car
 
-  xtil1car = xtild1*xtild1
-  xtil2car = xtild2*xtild2
+    !------------------------------------------------------------
 
-  derr = 2.*(xf2-xf1)/(xtild1-xtild2)
+    x1car = x1 * x1
+    x2car = x2 * x2
 
-  x1x2car = (xtild1-xtild2)*(xtild1-xtild2)
+    a3 = (2d0 * (y2-y1)/(x1-x2)+yp1+yp2)/((x1-x2) * (x1-x2))
+    a2 = (yp1-yp2+3d0 * a3 * (x2car-x1car))/(2d0 * (x1-x2))
 
-  a3 = (derr+xprim1+xprim2)/x1x2car
-  a2 = (xprim1-xprim2+3.*a3*(xtil2car-xtil1car))/(2.*(xtild1-xtild2))
+    a1 = yp1 - 3d0 * a3 * x1car - 2d0 * a2 * x1
+    a0 = y1 - a3 * x1 * x1car - a2 * x1car - a1 * x1
 
-  a1 = xprim1 - 3.*a3*xtil1car - 2.*a2*xtild1
-  a0 = xf1 - a3*xtild1*xtil1car - a2*xtil1car - a1*xtild1
+  END SUBROUTINE coefpoly
 
-END SUBROUTINE coefpoly
+end module coefpoly_m