| Line | |
|---|
| 1 | INTEGER FUNCTION ISAMAX(N,SX,INCX) |
|---|
| 2 | * .. Scalar Arguments .. |
|---|
| 3 | INTEGER INCX,N |
|---|
| 4 | * .. |
|---|
| 5 | * .. Array Arguments .. |
|---|
| 6 | REAL SX(*) |
|---|
| 7 | * .. |
|---|
| 8 | * |
|---|
| 9 | * Purpose |
|---|
| 10 | * ======= |
|---|
| 11 | * |
|---|
| 12 | * finds the index of element having max. absolute value. |
|---|
| 13 | * jack dongarra, linpack, 3/11/78. |
|---|
| 14 | * modified 3/93 to return if incx .le. 0. |
|---|
| 15 | * modified 12/3/93, array(1) declarations changed to array(*) |
|---|
| 16 | * |
|---|
| 17 | * |
|---|
| 18 | * .. Local Scalars .. |
|---|
| 19 | REAL SMAX |
|---|
| 20 | INTEGER I,IX |
|---|
| 21 | * .. |
|---|
| 22 | * .. Intrinsic Functions .. |
|---|
| 23 | INTRINSIC ABS |
|---|
| 24 | * .. |
|---|
| 25 | ISAMAX = 0 |
|---|
| 26 | IF (N.LT.1 .OR. INCX.LE.0) RETURN |
|---|
| 27 | ISAMAX = 1 |
|---|
| 28 | IF (N.EQ.1) RETURN |
|---|
| 29 | IF (INCX.EQ.1) GO TO 20 |
|---|
| 30 | * |
|---|
| 31 | * code for increment not equal to 1 |
|---|
| 32 | * |
|---|
| 33 | IX = 1 |
|---|
| 34 | SMAX = ABS(SX(1)) |
|---|
| 35 | IX = IX + INCX |
|---|
| 36 | DO 10 I = 2,N |
|---|
| 37 | IF (ABS(SX(IX)).LE.SMAX) GO TO 5 |
|---|
| 38 | ISAMAX = I |
|---|
| 39 | SMAX = ABS(SX(IX)) |
|---|
| 40 | 5 IX = IX + INCX |
|---|
| 41 | 10 CONTINUE |
|---|
| 42 | RETURN |
|---|
| 43 | * |
|---|
| 44 | * code for increment equal to 1 |
|---|
| 45 | * |
|---|
| 46 | 20 SMAX = ABS(SX(1)) |
|---|
| 47 | DO 30 I = 2,N |
|---|
| 48 | IF (ABS(SX(I)).LE.SMAX) GO TO 30 |
|---|
| 49 | ISAMAX = I |
|---|
| 50 | SMAX = ABS(SX(I)) |
|---|
| 51 | 30 CONTINUE |
|---|
| 52 | RETURN |
|---|
| 53 | END |
|---|
Note: See
TracBrowser
for help on using the repository browser.
