| [1] | 1 | ! |
|---|
| 2 | ! $Header$ |
|---|
| 3 | ! |
|---|
| 4 | SUBROUTINE coefpoly ( Xf1, Xf2, Xprim1, Xprim2, xtild1,xtild2 , |
|---|
| 5 | , a0,a1,a2,a3 ) |
|---|
| 6 | IMPLICIT NONE |
|---|
| 7 | c |
|---|
| 8 | c ... Auteur : P. Le Van ... |
|---|
| 9 | c |
|---|
| 10 | c |
|---|
| 11 | c Calcul des coefficients a0, a1, a2, a3 du polynome de degre 3 qui |
|---|
| 12 | c satisfait aux 4 equations suivantes : |
|---|
| 13 | |
|---|
| 14 | c a0 + a1*xtild1 + a2*xtild1*xtild1 + a3*xtild1*xtild1*xtild1 = Xf1 |
|---|
| 15 | c a0 + a1*xtild2 + a2*xtild2*xtild2 + a3*xtild2*xtild2*xtild2 = Xf2 |
|---|
| 16 | c a1 + 2.*a2*xtild1 + 3.*a3*xtild1*xtild1 = Xprim1 |
|---|
| 17 | c a1 + 2.*a2*xtild2 + 3.*a3*xtild2*xtild2 = Xprim2 |
|---|
| 18 | |
|---|
| 19 | c On en revient a resoudre un systeme de 4 equat.a 4 inconnues a0,a1,a2,a3 |
|---|
| 20 | |
|---|
| 21 | REAL(KIND=8) Xf1, Xf2,Xprim1,Xprim2, xtild1,xtild2, xi |
|---|
| 22 | REAL(KIND=8) Xfout, Xprim |
|---|
| 23 | REAL(KIND=8) a1,a2,a3,a0, xtil1car, xtil2car,derr,x1x2car |
|---|
| 24 | |
|---|
| 25 | 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 ) ) / |
|---|
| 34 | / ( 2.* ( xtild1 - xtild2 ) ) |
|---|
| 35 | |
|---|
| 36 | a1 = Xprim1 -3.* a3 * xtil1car -2.* a2 * xtild1 |
|---|
| 37 | a0 = Xf1 - a3 * xtild1* xtil1car -a2 * xtil1car - a1 *xtild1 |
|---|
| 38 | |
|---|
| 39 | RETURN |
|---|
| 40 | END |
|---|
