clascl.f

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      SUBROUTINE clascl( TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO )
*
*  -- LAPACK auxiliary routine (version 3.2) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2006
*
*     .. Scalar Arguments ..
      CHARACTER          type
      INTEGER            info, kl, ku, lda, m, n
      REAL               cfrom, cto
*     ..
*     .. Array Arguments ..
      COMPLEX            a( lda, * )
*     ..
*
*  Purpose
*  =======
*
*  CLASCL multiplies the M by N complex 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) REAL
*  CTO     (input) REAL
*          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) COMPLEX array, dimension (LDA,N)
*          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 ..
      REAL               zero, one
      parameter( zero = 0.0e0, one = 1.0e0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            done
      INTEGER            i, itype, j, k1, k2, k3, k4
      REAL               bignum, cfrom1, cfromc, cto1, ctoc, mul, smlnum
*     ..
*     .. External Functions ..
      LOGICAL            lsame, sisnan
      REAL               slamch
      EXTERNAL           lsame, slamch, sisnan
*     ..
*     .. 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 .OR. sisnan(cfrom) ) THEN
         info = -4
      ELSE IF( sisnan(cto) ) THEN
         info = -5
      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( 'CLASCL', -info )
         return
      END IF
*
*     Quick return if possible
*
      IF( n.EQ.0 .OR. m.EQ.0 )
     $   return
*
*     Get machine parameters
*
      smlnum = slamch( 'S' )
      bignum = one / smlnum
*
      cfromc = cfrom
      ctoc = cto
*
   10 continue
      cfrom1 = cfromc*smlnum
      IF( cfrom1.EQ.cfromc ) THEN
!        CFROMC is an inf.  Multiply by a correctly signed zero for
!        finite CTOC, or a NaN if CTOC is infinite.
         mul = ctoc / cfromc
         done = .true.
         cto1 = ctoc
      ELSE
         cto1 = ctoc / bignum
         IF( cto1.EQ.ctoc ) THEN
!           CTOC is either 0 or an inf.  In both cases, CTOC itself
!           serves as the correct multiplication factor.
            mul = ctoc
            done = .true.
            cfromc = one
         ELSE 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
      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 CLASCL
*
      END