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Diffstat (limited to '2.3-1/src/fortran/lapack/dlasrt.f')
| -rw-r--r-- | 2.3-1/src/fortran/lapack/dlasrt.f | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/lapack/dlasrt.f b/2.3-1/src/fortran/lapack/dlasrt.f new file mode 100644 index 00000000..37e02178 --- /dev/null +++ b/2.3-1/src/fortran/lapack/dlasrt.f @@ -0,0 +1,243 @@ + SUBROUTINE DLASRT( ID, N, D, INFO ) +* +* -- LAPACK routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + CHARACTER ID + INTEGER INFO, N +* .. +* .. Array Arguments .. + DOUBLE PRECISION D( * ) +* .. +* +* Purpose +* ======= +* +* Sort the numbers in D in increasing order (if ID = 'I') or +* in decreasing order (if ID = 'D' ). +* +* Use Quick Sort, reverting to Insertion sort on arrays of +* size <= 20. Dimension of STACK limits N to about 2**32. +* +* Arguments +* ========= +* +* ID (input) CHARACTER*1 +* = 'I': sort D in increasing order; +* = 'D': sort D in decreasing order. +* +* N (input) INTEGER +* The length of the array D. +* +* D (input/output) DOUBLE PRECISION array, dimension (N) +* On entry, the array to be sorted. +* On exit, D has been sorted into increasing order +* (D(1) <= ... <= D(N) ) or into decreasing order +* (D(1) >= ... >= D(N) ), depending on ID. +* +* INFO (output) INTEGER +* = 0: successful exit +* < 0: if INFO = -i, the i-th argument had an illegal value +* +* ===================================================================== +* +* .. Parameters .. + INTEGER SELECT + PARAMETER ( SELECT = 20 ) +* .. +* .. Local Scalars .. + INTEGER DIR, ENDD, I, J, START, STKPNT + DOUBLE PRECISION D1, D2, D3, DMNMX, TMP +* .. +* .. Local Arrays .. + INTEGER STACK( 2, 32 ) +* .. +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. +* .. External Subroutines .. + EXTERNAL XERBLA +* .. +* .. Executable Statements .. +* +* Test the input paramters. +* + INFO = 0 + DIR = -1 + IF( LSAME( ID, 'D' ) ) THEN + DIR = 0 + ELSE IF( LSAME( ID, 'I' ) ) THEN + DIR = 1 + END IF + IF( DIR.EQ.-1 ) THEN + INFO = -1 + ELSE IF( N.LT.0 ) THEN + INFO = -2 + END IF + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'DLASRT', -INFO ) + RETURN + END IF +* +* Quick return if possible +* + IF( N.LE.1 ) + $ RETURN +* + STKPNT = 1 + STACK( 1, 1 ) = 1 + STACK( 2, 1 ) = N + 10 CONTINUE + START = STACK( 1, STKPNT ) + ENDD = STACK( 2, STKPNT ) + STKPNT = STKPNT - 1 + IF( ENDD-START.LE.SELECT .AND. ENDD-START.GT.0 ) THEN +* +* Do Insertion sort on D( START:ENDD ) +* + IF( DIR.EQ.0 ) THEN +* +* Sort into decreasing order +* + DO 30 I = START + 1, ENDD + DO 20 J = I, START + 1, -1 + IF( D( J ).GT.D( J-1 ) ) THEN + DMNMX = D( J ) + D( J ) = D( J-1 ) + D( J-1 ) = DMNMX + ELSE + GO TO 30 + END IF + 20 CONTINUE + 30 CONTINUE +* + ELSE +* +* Sort into increasing order +* + DO 50 I = START + 1, ENDD + DO 40 J = I, START + 1, -1 + IF( D( J ).LT.D( J-1 ) ) THEN + DMNMX = D( J ) + D( J ) = D( J-1 ) + D( J-1 ) = DMNMX + ELSE + GO TO 50 + END IF + 40 CONTINUE + 50 CONTINUE +* + END IF +* + ELSE IF( ENDD-START.GT.SELECT ) THEN +* +* Partition D( START:ENDD ) and stack parts, largest one first +* +* Choose partition entry as median of 3 +* + D1 = D( START ) + D2 = D( ENDD ) + I = ( START+ENDD ) / 2 + D3 = D( I ) + IF( D1.LT.D2 ) THEN + IF( D3.LT.D1 ) THEN + DMNMX = D1 + ELSE IF( D3.LT.D2 ) THEN + DMNMX = D3 + ELSE + DMNMX = D2 + END IF + ELSE + IF( D3.LT.D2 ) THEN + DMNMX = D2 + ELSE IF( D3.LT.D1 ) THEN + DMNMX = D3 + ELSE + DMNMX = D1 + END IF + END IF +* + IF( DIR.EQ.0 ) THEN +* +* Sort into decreasing order +* + I = START - 1 + J = ENDD + 1 + 60 CONTINUE + 70 CONTINUE + J = J - 1 + IF( D( J ).LT.DMNMX ) + $ GO TO 70 + 80 CONTINUE + I = I + 1 + IF( D( I ).GT.DMNMX ) + $ GO TO 80 + IF( I.LT.J ) THEN + TMP = D( I ) + D( I ) = D( J ) + D( J ) = TMP + GO TO 60 + END IF + IF( J-START.GT.ENDD-J-1 ) THEN + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = START + STACK( 2, STKPNT ) = J + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = J + 1 + STACK( 2, STKPNT ) = ENDD + ELSE + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = J + 1 + STACK( 2, STKPNT ) = ENDD + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = START + STACK( 2, STKPNT ) = J + END IF + ELSE +* +* Sort into increasing order +* + I = START - 1 + J = ENDD + 1 + 90 CONTINUE + 100 CONTINUE + J = J - 1 + IF( D( J ).GT.DMNMX ) + $ GO TO 100 + 110 CONTINUE + I = I + 1 + IF( D( I ).LT.DMNMX ) + $ GO TO 110 + IF( I.LT.J ) THEN + TMP = D( I ) + D( I ) = D( J ) + D( J ) = TMP + GO TO 90 + END IF + IF( J-START.GT.ENDD-J-1 ) THEN + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = START + STACK( 2, STKPNT ) = J + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = J + 1 + STACK( 2, STKPNT ) = ENDD + ELSE + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = J + 1 + STACK( 2, STKPNT ) = ENDD + STKPNT = STKPNT + 1 + STACK( 1, STKPNT ) = START + STACK( 2, STKPNT ) = J + END IF + END IF + END IF + IF( STKPNT.GT.0 ) + $ GO TO 10 + RETURN +* +* End of DLASRT +* + END |