dormrz.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 318 行 · 第 1/2 页

      NOTRAN = <a name="LSAME.141"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'N'</span> )
      LQUERY = ( LWORK.EQ.-1 )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     NQ is the order of Q and NW is the minimum dimension of WORK
</span><span class="comment">*</span><span class="comment">
</span>      IF( LEFT ) THEN
         NQ = M
         NW = MAX( 1, N )
      ELSE
         NQ = N
         NW = MAX( 1, M )
      END IF
      IF( .NOT.LEFT .AND. .NOT.<a name="LSAME.153"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( SIDE, <span class="string">'R'</span> ) ) THEN
         INFO = -1
      ELSE IF( .NOT.NOTRAN .AND. .NOT.<a name="LSAME.155"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'T'</span> ) ) THEN
         INFO = -2
      ELSE IF( M.LT.0 ) THEN
         INFO = -3
      ELSE IF( N.LT.0 ) THEN
         INFO = -4
      ELSE IF( K.LT.0 .OR. K.GT.NQ ) THEN
         INFO = -5
      ELSE IF( L.LT.0 .OR. ( LEFT .AND. ( L.GT.M ) ) .OR.
     $         ( .NOT.LEFT .AND. ( L.GT.N ) ) ) THEN
         INFO = -6
      ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
         INFO = -8
      ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
         INFO = -11
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.EQ.0 ) THEN
         IF( M.EQ.0 .OR. N.EQ.0 ) THEN
            LWKOPT = 1
         ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Determine the block size.  NB may be at most NBMAX, where
</span><span class="comment">*</span><span class="comment">           NBMAX is used to define the local array T.
</span><span class="comment">*</span><span class="comment">
</span>            NB = MIN( NBMAX, <a name="ILAENV.180"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="DORMRQ.180"></a><a href="dormrq.f.html#DORMRQ.1">DORMRQ</a>'</span>, SIDE // TRANS, M, N,
     $                               K, -1 ) )
            LWKOPT = NW*NB
         END IF
         WORK( 1 ) = LWKOPT
<span class="comment">*</span><span class="comment">
</span>         IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
            INFO = -13
         END IF
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.192"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="DORMRZ.192"></a><a href="dormrz.f.html#DORMRZ.1">DORMRZ</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( M.EQ.0 .OR. N.EQ.0 ) THEN
         WORK( 1 ) = 1
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span>      NBMIN = 2
      LDWORK = NW
      IF( NB.GT.1 .AND. NB.LT.K ) THEN
         IWS = NW*NB
         IF( LWORK.LT.IWS ) THEN
            NB = LWORK / LDWORK
            NBMIN = MAX( 2, <a name="ILAENV.211"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 2, <span class="string">'<a name="DORMRQ.211"></a><a href="dormrq.f.html#DORMRQ.1">DORMRQ</a>'</span>, SIDE // TRANS, M, N, K,
     $              -1 ) )
         END IF
      ELSE
         IWS = NW
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( NB.LT.NBMIN .OR. NB.GE.K ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Use unblocked code
</span><span class="comment">*</span><span class="comment">
</span>         CALL <a name="DORMR3.222"></a><a href="dormr3.f.html#DORMR3.1">DORMR3</a>( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
     $                WORK, IINFO )
      ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Use blocked code
</span><span class="comment">*</span><span class="comment">
</span>         IF( ( LEFT .AND. .NOT.NOTRAN ) .OR.
     $       ( .NOT.LEFT .AND. NOTRAN ) ) THEN
            I1 = 1
            I2 = K
            I3 = NB
         ELSE
            I1 = ( ( K-1 ) / NB )*NB + 1
            I2 = 1
            I3 = -NB
         END IF
<span class="comment">*</span><span class="comment">
</span>         IF( LEFT ) THEN
            NI = N
            JC = 1
            JA = M - L + 1
         ELSE
            MI = M
            IC = 1
            JA = N - L + 1
         END IF
<span class="comment">*</span><span class="comment">
</span>         IF( NOTRAN ) THEN
            TRANST = <span class="string">'T'</span>
         ELSE
            TRANST = <span class="string">'N'</span>
         END IF
<span class="comment">*</span><span class="comment">
</span>         DO 10 I = I1, I2, I3
            IB = MIN( NB, K-I+1 )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Form the triangular factor of the block reflector
</span><span class="comment">*</span><span class="comment">           H = H(i+ib-1) . . . H(i+1) H(i)
</span><span class="comment">*</span><span class="comment">
</span>            CALL <a name="DLARZT.261"></a><a href="dlarzt.f.html#DLARZT.1">DLARZT</a>( <span class="string">'Backward'</span>, <span class="string">'Rowwise'</span>, L, IB, A( I, JA ), LDA,
     $                   TAU( I ), T, LDT )
<span class="comment">*</span><span class="comment">
</span>            IF( LEFT ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              H or H' is applied to C(i:m,1:n)
</span><span class="comment">*</span><span class="comment">
</span>               MI = M - I + 1
               IC = I
            ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              H or H' is applied to C(1:m,i:n)
</span><span class="comment">*</span><span class="comment">
</span>               NI = N - I + 1
               JC = I
            END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Apply H or H'
</span><span class="comment">*</span><span class="comment">
</span>            CALL <a name="DLARZB.280"></a><a href="dlarzb.f.html#DLARZB.1">DLARZB</a>( SIDE, TRANST, <span class="string">'Backward'</span>, <span class="string">'Rowwise'</span>, MI, NI,
     $                   IB, L, A( I, JA ), LDA, T, LDT, C( IC, JC ),
     $                   LDC, WORK, LDWORK )
   10    CONTINUE
<span class="comment">*</span><span class="comment">
</span>      END IF
<span class="comment">*</span><span class="comment">
</span>      WORK( 1 ) = LWKOPT
<span class="comment">*</span><span class="comment">
</span>      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="DORMRZ.291"></a><a href="dormrz.f.html#DORMRZ.1">DORMRZ</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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