diff libcruft/lapack/dlascl.f @ 2329:30c606bec7a8

[project @ 1996-07-19 01:29:05 by jwe] Initial revision
author jwe
date Fri, 19 Jul 1996 01:29:55 +0000
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children 15cddaacbc2d
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+      SUBROUTINE DLASCL( TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO )
+*
+*  -- LAPACK auxiliary routine (version 2.0) --
+*     Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
+*     Courant Institute, Argonne National Lab, and Rice University
+*     February 29, 1992
+*
+*     .. Scalar Arguments ..
+      CHARACTER          TYPE
+      INTEGER            INFO, KL, KU, LDA, M, N
+      DOUBLE PRECISION   CFROM, CTO
+*     ..
+*     .. Array Arguments ..
+      DOUBLE PRECISION   A( LDA, * )
+*     ..
+*
+*  Purpose
+*  =======
+*
+*  DLASCL multiplies the M by N real matrix A by the real scalar
+*  CTO/CFROM.  This is done without over/underflow as long as the final
+*  result CTO*A(I,J)/CFROM does not over/underflow. TYPE specifies that
+*  A may be full, upper triangular, lower triangular, upper Hessenberg,
+*  or banded.
+*
+*  Arguments
+*  =========
+*
+*  TYPE    (input) CHARACTER*1
+*          TYPE indices the storage type of the input matrix.
+*          = 'G':  A is a full matrix.
+*          = 'L':  A is a lower triangular matrix.
+*          = 'U':  A is an upper triangular matrix.
+*          = 'H':  A is an upper Hessenberg matrix.
+*          = 'B':  A is a symmetric band matrix with lower bandwidth KL
+*                  and upper bandwidth KU and with the only the lower
+*                  half stored.
+*          = 'Q':  A is a symmetric band matrix with lower bandwidth KL
+*                  and upper bandwidth KU and with the only the upper
+*                  half stored.
+*          = 'Z':  A is a band matrix with lower bandwidth KL and upper
+*                  bandwidth KU.
+*
+*  KL      (input) INTEGER
+*          The lower bandwidth of A.  Referenced only if TYPE = 'B',
+*          'Q' or 'Z'.
+*
+*  KU      (input) INTEGER
+*          The upper bandwidth of A.  Referenced only if TYPE = 'B',
+*          'Q' or 'Z'.
+*
+*  CFROM   (input) DOUBLE PRECISION
+*  CTO     (input) DOUBLE PRECISION
+*          The matrix A is multiplied by CTO/CFROM. A(I,J) is computed
+*          without over/underflow if the final result CTO*A(I,J)/CFROM
+*          can be represented without over/underflow.  CFROM must be
+*          nonzero.
+*
+*  M       (input) INTEGER
+*          The number of rows of the matrix A.  M >= 0.
+*
+*  N       (input) INTEGER
+*          The number of columns of the matrix A.  N >= 0.
+*
+*  A       (input/output) DOUBLE PRECISION array, dimension (LDA,M)
+*          The matrix to be multiplied by CTO/CFROM.  See TYPE for the
+*          storage type.
+*
+*  LDA     (input) INTEGER
+*          The leading dimension of the array A.  LDA >= max(1,M).
+*
+*  INFO    (output) INTEGER
+*          0  - successful exit
+*          <0 - if INFO = -i, the i-th argument had an illegal value.
+*
+*  =====================================================================
+*
+*     .. Parameters ..
+      DOUBLE PRECISION   ZERO, ONE
+      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
+*     ..
+*     .. Local Scalars ..
+      LOGICAL            DONE
+      INTEGER            I, ITYPE, J, K1, K2, K3, K4
+      DOUBLE PRECISION   BIGNUM, CFROM1, CFROMC, CTO1, CTOC, MUL, SMLNUM
+*     ..
+*     .. External Functions ..
+      LOGICAL            LSAME
+      DOUBLE PRECISION   DLAMCH
+      EXTERNAL           LSAME, DLAMCH
+*     ..
+*     .. Intrinsic Functions ..
+      INTRINSIC          ABS, MAX, MIN
+*     ..
+*     .. External Subroutines ..
+      EXTERNAL           XERBLA
+*     ..
+*     .. Executable Statements ..
+*
+*     Test the input arguments
+*
+      INFO = 0
+*
+      IF( LSAME( TYPE, 'G' ) ) THEN
+         ITYPE = 0
+      ELSE IF( LSAME( TYPE, 'L' ) ) THEN
+         ITYPE = 1
+      ELSE IF( LSAME( TYPE, 'U' ) ) THEN
+         ITYPE = 2
+      ELSE IF( LSAME( TYPE, 'H' ) ) THEN
+         ITYPE = 3
+      ELSE IF( LSAME( TYPE, 'B' ) ) THEN
+         ITYPE = 4
+      ELSE IF( LSAME( TYPE, 'Q' ) ) THEN
+         ITYPE = 5
+      ELSE IF( LSAME( TYPE, 'Z' ) ) THEN
+         ITYPE = 6
+      ELSE
+         ITYPE = -1
+      END IF
+*
+      IF( ITYPE.EQ.-1 ) THEN
+         INFO = -1
+      ELSE IF( CFROM.EQ.ZERO ) THEN
+         INFO = -4
+      ELSE IF( M.LT.0 ) THEN
+         INFO = -6
+      ELSE IF( N.LT.0 .OR. ( ITYPE.EQ.4 .AND. N.NE.M ) .OR.
+     $         ( ITYPE.EQ.5 .AND. N.NE.M ) ) THEN
+         INFO = -7
+      ELSE IF( ITYPE.LE.3 .AND. LDA.LT.MAX( 1, M ) ) THEN
+         INFO = -9
+      ELSE IF( ITYPE.GE.4 ) THEN
+         IF( KL.LT.0 .OR. KL.GT.MAX( M-1, 0 ) ) THEN
+            INFO = -2
+         ELSE IF( KU.LT.0 .OR. KU.GT.MAX( N-1, 0 ) .OR.
+     $            ( ( ITYPE.EQ.4 .OR. ITYPE.EQ.5 ) .AND. KL.NE.KU ) )
+     $             THEN
+            INFO = -3
+         ELSE IF( ( ITYPE.EQ.4 .AND. LDA.LT.KL+1 ) .OR.
+     $            ( ITYPE.EQ.5 .AND. LDA.LT.KU+1 ) .OR.
+     $            ( ITYPE.EQ.6 .AND. LDA.LT.2*KL+KU+1 ) ) THEN
+            INFO = -9
+         END IF
+      END IF
+*
+      IF( INFO.NE.0 ) THEN
+         CALL XERBLA( 'DLASCL', -INFO )
+         RETURN
+      END IF
+*
+*     Quick return if possible
+*
+      IF( N.EQ.0 .OR. M.EQ.0 )
+     $   RETURN
+*
+*     Get machine parameters
+*
+      SMLNUM = DLAMCH( 'S' )
+      BIGNUM = ONE / SMLNUM
+*
+      CFROMC = CFROM
+      CTOC = CTO
+*
+   10 CONTINUE
+      CFROM1 = CFROMC*SMLNUM
+      CTO1 = CTOC / BIGNUM
+      IF( ABS( CFROM1 ).GT.ABS( CTOC ) .AND. CTOC.NE.ZERO ) THEN
+         MUL = SMLNUM
+         DONE = .FALSE.
+         CFROMC = CFROM1
+      ELSE IF( ABS( CTO1 ).GT.ABS( CFROMC ) ) THEN
+         MUL = BIGNUM
+         DONE = .FALSE.
+         CTOC = CTO1
+      ELSE
+         MUL = CTOC / CFROMC
+         DONE = .TRUE.
+      END IF
+*
+      IF( ITYPE.EQ.0 ) THEN
+*
+*        Full matrix
+*
+         DO 30 J = 1, N
+            DO 20 I = 1, M
+               A( I, J ) = A( I, J )*MUL
+   20       CONTINUE
+   30    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.1 ) THEN
+*
+*        Lower triangular matrix
+*
+         DO 50 J = 1, N
+            DO 40 I = J, M
+               A( I, J ) = A( I, J )*MUL
+   40       CONTINUE
+   50    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.2 ) THEN
+*
+*        Upper triangular matrix
+*
+         DO 70 J = 1, N
+            DO 60 I = 1, MIN( J, M )
+               A( I, J ) = A( I, J )*MUL
+   60       CONTINUE
+   70    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.3 ) THEN
+*
+*        Upper Hessenberg matrix
+*
+         DO 90 J = 1, N
+            DO 80 I = 1, MIN( J+1, M )
+               A( I, J ) = A( I, J )*MUL
+   80       CONTINUE
+   90    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.4 ) THEN
+*
+*        Lower half of a symmetric band matrix
+*
+         K3 = KL + 1
+         K4 = N + 1
+         DO 110 J = 1, N
+            DO 100 I = 1, MIN( K3, K4-J )
+               A( I, J ) = A( I, J )*MUL
+  100       CONTINUE
+  110    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.5 ) THEN
+*
+*        Upper half of a symmetric band matrix
+*
+         K1 = KU + 2
+         K3 = KU + 1
+         DO 130 J = 1, N
+            DO 120 I = MAX( K1-J, 1 ), K3
+               A( I, J ) = A( I, J )*MUL
+  120       CONTINUE
+  130    CONTINUE
+*
+      ELSE IF( ITYPE.EQ.6 ) THEN
+*
+*        Band matrix
+*
+         K1 = KL + KU + 2
+         K2 = KL + 1
+         K3 = 2*KL + KU + 1
+         K4 = KL + KU + 1 + M
+         DO 150 J = 1, N
+            DO 140 I = MAX( K1-J, K2 ), MIN( K3, K4-J )
+               A( I, J ) = A( I, J )*MUL
+  140       CONTINUE
+  150    CONTINUE
+*
+      END IF
+*
+      IF( .NOT.DONE )
+     $   GO TO 10
+*
+      RETURN
+*
+*     End of DLASCL
+*
+      END