--- trunk/libf/dyn3d/coefpoly.f	2013/07/08 18:12:18	71
+++ trunk/Sources/dyn3d/coefpoly.f	2015/06/16 17:27:33	146
@@ -1,40 +1,42 @@
-!
-! $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
-c
-c   ...  Auteur :   P. Le Van  ...
-c
-c
-c    Calcul des coefficients a0, a1, a2, a3 du polynome de degre 3 qui
-c      satisfait aux 4 equations  suivantes :
-
-c    a0 + a1*xtild1 + a2*xtild1*xtild1 + a3*xtild1*xtild1*xtild1 = Xf1
-c    a0 + a1*xtild2 + a2*xtild2*xtild2 + a3*xtild2*xtild2*xtild2 = Xf2
-c               a1  +     2.*a2*xtild1 +     3.*a3*xtild1*xtild1 = Xprim1
-c               a1  +     2.*a2*xtild2 +     3.*a3*xtild2*xtild2 = Xprim2
-
-c  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 )  )
+module coefpoly_m
 
-      a1     = Xprim1 -3.* a3 * xtil1car     -2.* a2 * xtild1
-      a0     =  Xf1 - a3 * xtild1* xtil1car -a2 * xtil1car - a1 *xtild1
+  IMPLICIT NONE
 
-      RETURN
-      END
+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 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 * 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
+
+    DOUBLE PRECISION, intent(in):: y1, y2, yp1, yp2, x1, x2
+    DOUBLE PRECISION, intent(out):: a0, a1, a2, a3
+
+    ! Local:
+    DOUBLE PRECISION x1car, x2car
+
+    !------------------------------------------------------------
+
+    x1car = x1 * x1
+    x2car = x2 * x2
+
+    a3 = (2d0 * (y2-y1)/(x1-x2)+yp1+yp2)/((x1-x2) * (x1-x2))
+    a2 = (yp1-yp2+3d0 * a3 * (x2car-x1car))/(2d0 * (x1-x2))
+
+    a1 = yp1 - 3d0 * a3 * x1car - 2d0 * a2 * x1
+    a0 = y1 - a3 * x1 * x1car - a2 * x1car - a1 * x1
+
+  END SUBROUTINE coefpoly
+
+end module coefpoly_m