dgelsy.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 416 行 · 第 1/3 页

</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">
</span><span class="comment">*</span><span class="comment">  Further Details
</span><span class="comment">*</span><span class="comment">  ===============
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">  Based on contributions by
</span><span class="comment">*</span><span class="comment">    A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
</span><span class="comment">*</span><span class="comment">    E. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
</span><span class="comment">*</span><span class="comment">    G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
</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>      INTEGER            IMAX, IMIN
      PARAMETER          ( IMAX = 1, IMIN = 2 )
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D+0, ONE = 1.0D+0 )
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      LOGICAL            LQUERY
      INTEGER            I, IASCL, IBSCL, ISMAX, ISMIN, J, LWKMIN,
     $                   LWKOPT, MN, NB, NB1, NB2, NB3, NB4
      DOUBLE PRECISION   ANRM, BIGNUM, BNRM, C1, C2, S1, S2, SMAX,
     $                   SMAXPR, SMIN, SMINPR, SMLNUM, WSIZE
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      INTEGER            <a name="ILAENV.149"></a><a href="hfy-index.html#ILAENV">ILAENV</a>
      DOUBLE PRECISION   <a name="DLAMCH.150"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="DLANGE.150"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>
      EXTERNAL           <a name="ILAENV.151"></a><a href="hfy-index.html#ILAENV">ILAENV</a>, <a name="DLAMCH.151"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>, <a name="DLANGE.151"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           DCOPY, <a name="DGEQP3.154"></a><a href="dgeqp3.f.html#DGEQP3.1">DGEQP3</a>, <a name="DLABAD.154"></a><a href="dlabad.f.html#DLABAD.1">DLABAD</a>, <a name="DLAIC1.154"></a><a href="dlaic1.f.html#DLAIC1.1">DLAIC1</a>, <a name="DLASCL.154"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>, <a name="DLASET.154"></a><a href="dlaset.f.html#DLASET.1">DLASET</a>,
     $                   <a name="DORMQR.155"></a><a href="dormqr.f.html#DORMQR.1">DORMQR</a>, <a name="DORMRZ.155"></a><a href="dormrz.f.html#DORMRZ.1">DORMRZ</a>, DTRSM, <a name="DTZRZF.155"></a><a href="dtzrzf.f.html#DTZRZF.1">DTZRZF</a>, <a name="XERBLA.155"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC          ABS, MAX, MIN
<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>      MN = MIN( M, N )
      ISMIN = MN + 1
      ISMAX = 2*MN + 1
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Test the input arguments.
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
      LQUERY = ( LWORK.EQ.-1 )
      IF( M.LT.0 ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -3
      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
         INFO = -5
      ELSE IF( LDB.LT.MAX( 1, M, N ) ) THEN
         INFO = -7
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Figure out optimal block size
</span><span class="comment">*</span><span class="comment">
</span>      IF( INFO.EQ.0 ) THEN
         IF( MN.EQ.0 .OR. NRHS.EQ.0 ) THEN
            LWKMIN = 1
            LWKOPT = 1
         ELSE
            NB1 = <a name="ILAENV.189"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGEQRF.189"></a><a href="dgeqrf.f.html#DGEQRF.1">DGEQRF</a>'</span>, <span class="string">' '</span>, M, N, -1, -1 )
            NB2 = <a name="ILAENV.190"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DGERQF.190"></a><a href="dgerqf.f.html#DGERQF.1">DGERQF</a>'</span>, <span class="string">' '</span>, M, N, -1, -1 )
            NB3 = <a name="ILAENV.191"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMQR.191"></a><a href="dormqr.f.html#DORMQR.1">DORMQR</a>'</span>, <span class="string">' '</span>, M, N, NRHS, -1 )
            NB4 = <a name="ILAENV.192"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMRQ.192"></a><a href="dormrq.f.html#DORMRQ.1">DORMRQ</a>'</span>, <span class="string">' '</span>, M, N, NRHS, -1 )
            NB = MAX( NB1, NB2, NB3, NB4 )
            LWKMIN = MN + MAX( 2*MN, N + 1, MN + NRHS )
            LWKOPT = MAX( LWKMIN,
     $                    MN + 2*N + NB*( N + 1 ), 2*MN + NB*NRHS )
         END IF
         WORK( 1 ) = LWKOPT
<span class="comment">*</span><span class="comment">
</span>         IF( LWORK.LT.LWKMIN .AND. .NOT.LQUERY ) THEN
            INFO = -12
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.206"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="DGELSY.206"></a><a href="dgelsy.f.html#DGELSY.1">DGELSY</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>      IF( MN.EQ.0 .OR. NRHS.EQ.0 ) THEN
         RANK = 0
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Get machine parameters
</span><span class="comment">*</span><span class="comment">
</span>      SMLNUM = <a name="DLAMCH.221"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>( <span class="string">'S'</span> ) / <a name="DLAMCH.221"></a><a href="dlamch.f.html#DLAMCH.1">DLAMCH</a>( <span class="string">'P'</span> )
      BIGNUM = ONE / SMLNUM
      CALL <a name="DLABAD.223"></a><a href="dlabad.f.html#DLABAD.1">DLABAD</a>( SMLNUM, BIGNUM )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Scale A, B if max entries outside range [SMLNUM,BIGNUM]
</span><span class="comment">*</span><span class="comment">
</span>      ANRM = <a name="DLANGE.227"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>( <span class="string">'M'</span>, M, N, A, LDA, WORK )
      IASCL = 0
      IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Scale matrix norm up to SMLNUM
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DLASCL.233"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, ANRM, SMLNUM, M, N, A, LDA, INFO )
         IASCL = 1
      ELSE IF( ANRM.GT.BIGNUM ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Scale matrix norm down to BIGNUM
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DLASCL.239"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, ANRM, BIGNUM, M, N, A, LDA, INFO )
         IASCL = 2
      ELSE IF( ANRM.EQ.ZERO ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Matrix all zero. Return zero solution.
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DLASET.245"></a><a href="dlaset.f.html#DLASET.1">DLASET</a>( <span class="string">'F'</span>, MAX( M, N ), NRHS, ZERO, ZERO, B, LDB )
         RANK = 0
         GO TO 70
      END IF
<span class="comment">*</span><span class="comment">
</span>      BNRM = <a name="DLANGE.250"></a><a href="dlange.f.html#DLANGE.1">DLANGE</a>( <span class="string">'M'</span>, M, NRHS, B, LDB, WORK )
      IBSCL = 0
      IF( BNRM.GT.ZERO .AND. BNRM.LT.SMLNUM ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Scale matrix norm up to SMLNUM
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DLASCL.256"></a><a href="dlascl.f.html#DLASCL.1">DLASCL</a>( <span class="string">'G'</span>, 0, 0, BNRM, SMLNUM, M, NRHS, B, LDB, INFO )
         IBSCL = 1
      ELSE IF( BNRM.GT.BIGNUM ) THEN
<span class="comment">*</span><span class="comment">