zheevx.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 464 行 · 第 1/3 页

</span><span class="comment">*</span><span class="comment">  RWORK   (workspace) DOUBLE PRECISION array, dimension (7*N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  IWORK   (workspace) INTEGER array, dimension (5*N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  IFAIL   (output) INTEGER array, dimension (N)
</span><span class="comment">*</span><span class="comment">          If JOBZ = 'V', then if INFO = 0, the first M elements of
</span><span class="comment">*</span><span class="comment">          IFAIL are zero.  If INFO &gt; 0, then IFAIL contains the
</span><span class="comment">*</span><span class="comment">          indices of the eigenvectors that failed to converge.
</span><span class="comment">*</span><span class="comment">          If JOBZ = 'N', then IFAIL is not referenced.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  INFO    (output) INTEGER
</span><span class="comment">*</span><span class="comment">          = 0:  successful exit
</span><span class="comment">*</span><span class="comment">          &lt; 0:  if INFO = -i, the i-th argument had an illegal value
</span><span class="comment">*</span><span class="comment">          &gt; 0:  if INFO = i, then i eigenvectors failed to converge.
</span><span class="comment">*</span><span class="comment">                Their indices are stored in array IFAIL.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     .. Parameters ..
</span>      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
      COMPLEX*16         CONE
      PARAMETER          ( CONE = ( 1.0D+0, 0.0D+0 ) )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      LOGICAL            ALLEIG, INDEIG, LOWER, LQUERY, TEST, VALEIG,
     $                   WANTZ
      CHARACTER          ORDER
      INTEGER            I, IINFO, IMAX, INDD, INDE, INDEE, INDIBL,
     $                   INDISP, INDIWK, INDRWK, INDTAU, INDWRK, ISCALE,
     $                   ITMP1, J, JJ, LLWORK, LWKMIN, LWKOPT, NB,
     $                   NSPLIT
      DOUBLE PRECISION   ABSTLL, ANRM, BIGNUM, EPS, RMAX, RMIN, SAFMIN,
     $                   SIGMA, SMLNUM, TMP1, VLL, VUU
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      LOGICAL            <a name="LSAME.173"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
      INTEGER            <a name="ILAENV.174"></a><a href="hfy-index.html#ILAENV">ILAENV</a>
      DOUBLE PRECISION   <a name="DLAMCH.175"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="ZLANHE.175"></a><a href="zlanhe.f.html#ZLANHE.1">ZLANHE</a>
      EXTERNAL           <a name="LSAME.176"></a><a href="lsame.f.html#LSAME.1">LSAME</a>, <a name="ILAENV.176"></a><a href="hfy-index.html#ILAENV">ILAENV</a>, <a name="DLAMCH.176"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="ZLANHE.176"></a><a href="zlanhe.f.html#ZLANHE.1">ZLANHE</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           DCOPY, DSCAL, <a name="DSTEBZ.179"></a><a href="dstebz.f.html#DSTEBZ.1">DSTEBZ</a>, <a name="DSTERF.179"></a><a href="dsterf.f.html#DSTERF.1">DSTERF</a>, <a name="XERBLA.179"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>, ZDSCAL,
     $                   <a name="ZHETRD.180"></a><a href="zhetrd.f.html#ZHETRD.1">ZHETRD</a>, <a name="ZLACPY.180"></a><a href="zlacpy.f.html#ZLACPY.1">ZLACPY</a>, <a name="ZSTEIN.180"></a><a href="zstein.f.html#ZSTEIN.1">ZSTEIN</a>, <a name="ZSTEQR.180"></a><a href="zsteqr.f.html#ZSTEQR.1">ZSTEQR</a>, ZSWAP, <a name="ZUNGTR.180"></a><a href="zungtr.f.html#ZUNGTR.1">ZUNGTR</a>,
     $                   <a name="ZUNMTR.181"></a><a href="zunmtr.f.html#ZUNMTR.1">ZUNMTR</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          DBLE, MAX, MIN, SQRT
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Executable Statements ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Test the input parameters.
</span><span class="comment">*</span><span class="comment">
</span>      LOWER = <a name="LSAME.190"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( UPLO, <span class="string">'L'</span> )
      WANTZ = <a name="LSAME.191"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'V'</span> )
      ALLEIG = <a name="LSAME.192"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( RANGE, <span class="string">'A'</span> )
      VALEIG = <a name="LSAME.193"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( RANGE, <span class="string">'V'</span> )
      INDEIG = <a name="LSAME.194"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( RANGE, <span class="string">'I'</span> )
      LQUERY = ( LWORK.EQ.-1 )
<span class="comment">*</span><span class="comment">
</span>      INFO = 0
      IF( .NOT.( WANTZ .OR. <a name="LSAME.198"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( JOBZ, <span class="string">'N'</span> ) ) ) THEN
         INFO = -1
      ELSE IF( .NOT.( ALLEIG .OR. VALEIG .OR. INDEIG ) ) THEN
         INFO = -2
      ELSE IF( .NOT.( LOWER .OR. <a name="LSAME.202"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( UPLO, <span class="string">'U'</span> ) ) ) THEN
         INFO = -3
      ELSE IF( N.LT.0 ) THEN
         INFO = -4
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -6
      ELSE
         IF( VALEIG ) THEN
            IF( N.GT.0 .AND. VU.LE.VL )
     $         INFO = -8
         ELSE IF( INDEIG ) THEN
            IF( IL.LT.1 .OR. IL.GT.MAX( 1, N ) ) THEN
               INFO = -9
            ELSE IF( IU.LT.MIN( N, IL ) .OR. IU.GT.N ) THEN
               INFO = -10
            END IF
         END IF
      END IF
      IF( INFO.EQ.0 ) THEN
         IF( LDZ.LT.1 .OR. ( WANTZ .AND. LDZ.LT.N ) ) THEN
            INFO = -15
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.EQ.0 ) THEN
         IF( N.LE.1 ) THEN
            LWKMIN = 1
            WORK( 1 ) = LWKMIN
         ELSE
            LWKMIN = 2*N
            NB = <a name="ILAENV.232"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="ZHETRD.232"></a><a href="zhetrd.f.html#ZHETRD.1">ZHETRD</a>'</span>, UPLO, N, -1, -1, -1 )
            NB = MAX( NB, <a name="ILAENV.233"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="ZUNMTR.233"></a><a href="zunmtr.f.html#ZUNMTR.1">ZUNMTR</a>'</span>, UPLO, N, -1, -1, -1 ) )
            LWKOPT = MAX( 1, ( NB + 1 )*N )
            WORK( 1 ) = LWKOPT
         END IF
<span class="comment">*</span><span class="comment">
</span>         IF( LWORK.LT.MAX( 1, 2*N ) .AND. .NOT.LQUERY )
     $      INFO = -17
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.243"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="ZHEEVX.243"></a><a href="zheevx.f.html#ZHEEVX.1">ZHEEVX</a>'</span>, -INFO )
         RETURN
      ELSE IF( LQUERY ) THEN
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Quick return if possible
</span><span class="comment">*</span><span class="comment">
</span>      M = 0
      IF( N.EQ.0 ) THEN
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( N.EQ.1 ) THEN
         IF( ALLEIG .OR. INDEIG ) THEN
            M = 1
            W( 1 ) = A( 1, 1 )
         ELSE IF( VALEIG ) THEN
            IF( VL.LT.DBLE( A( 1, 1 ) ) .AND. VU.GE.DBLE( A( 1, 1 ) ) )
     $           THEN
               M = 1
               W( 1 ) = A( 1, 1 )
            END IF
         END IF
         IF( WANTZ )
     $      Z( 1, 1 ) = CONE
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Get machine constants.
</span><span class="comment">*</span><span class="comment">
</span>      SAFMIN = <a name="DLAMCH.274"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>( <span class="string">'Safe minimum'</span> )
      EPS = <a name="DLAMCH.275"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>( <span class="string">'Precision'</span> )
      SMLNUM = SAFMIN / EPS
      BIGNUM = ONE / SMLNUM
      RMIN = SQRT( SMLNUM )
      RMAX = MIN( SQRT( BIGNUM ), ONE / SQRT( SQRT( SAFMIN ) ) )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Scale matrix to allowable range, if necessary.
</span><span class="comment">*</span><span class="comment">
</span>      ISCALE = 0
      ABSTLL = ABSTOL
      IF( VALEIG ) THEN
         VLL = VL
         VUU = VU
      END IF
      ANRM = <a name="ZLANHE.289"></a><a href="zlanhe.f.html#ZLANHE.1">ZLANHE</a>( <span class="string">'M'</span>, UPLO, N, A, LDA, RWORK )
      IF( ANRM.GT.ZERO .AND. ANRM.LT.RMIN ) THEN
         ISCALE = 1