root / src / blas / zrotg.f @ 4
Historique | Voir | Annoter | Télécharger (797 octet)
| 1 | 1 | pfleura2 | SUBROUTINE ZROTG(CA,CB,C,S) |
|---|---|---|---|
| 2 | 1 | pfleura2 | * .. Scalar Arguments .. |
| 3 | 1 | pfleura2 | DOUBLE COMPLEX CA,CB,S |
| 4 | 1 | pfleura2 | DOUBLE PRECISION C |
| 5 | 1 | pfleura2 | * .. |
| 6 | 1 | pfleura2 | * |
| 7 | 1 | pfleura2 | * Purpose |
| 8 | 1 | pfleura2 | * ======= |
| 9 | 1 | pfleura2 | * |
| 10 | 1 | pfleura2 | * determines a double complex Givens rotation. |
| 11 | 1 | pfleura2 | * |
| 12 | 1 | pfleura2 | * .. Local Scalars .. |
| 13 | 1 | pfleura2 | DOUBLE COMPLEX ALPHA |
| 14 | 1 | pfleura2 | DOUBLE PRECISION NORM,SCALE |
| 15 | 1 | pfleura2 | * .. |
| 16 | 1 | pfleura2 | * .. Intrinsic Functions .. |
| 17 | 1 | pfleura2 | INTRINSIC CDABS,DCMPLX,DCONJG,DSQRT |
| 18 | 1 | pfleura2 | * .. |
| 19 | 1 | pfleura2 | IF (CDABS(CA).NE.0.0d0) GO TO 10 |
| 20 | 1 | pfleura2 | C = 0.0d0 |
| 21 | 1 | pfleura2 | S = (1.0d0,0.0d0) |
| 22 | 1 | pfleura2 | CA = CB |
| 23 | 1 | pfleura2 | GO TO 20 |
| 24 | 1 | pfleura2 | 10 CONTINUE |
| 25 | 1 | pfleura2 | SCALE = CDABS(CA) + CDABS(CB) |
| 26 | 1 | pfleura2 | NORM = SCALE*DSQRT((CDABS(CA/DCMPLX(SCALE,0.0d0)))**2+ |
| 27 | 1 | pfleura2 | + (CDABS(CB/DCMPLX(SCALE,0.0d0)))**2) |
| 28 | 1 | pfleura2 | ALPHA = CA/CDABS(CA) |
| 29 | 1 | pfleura2 | C = CDABS(CA)/NORM |
| 30 | 1 | pfleura2 | S = ALPHA*DCONJG(CB)/NORM |
| 31 | 1 | pfleura2 | CA = ALPHA*NORM |
| 32 | 1 | pfleura2 | 20 CONTINUE |
| 33 | 1 | pfleura2 | RETURN |
| 34 | 1 | pfleura2 | END |