slarzb.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 245 行 · 第 1/2 页

      INTEGER            I, INFO, J
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Functions ..
</span>      LOGICAL            <a name="LSAME.108"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
      EXTERNAL           <a name="LSAME.109"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. External Subroutines ..
</span>      EXTERNAL           SCOPY, SGEMM, STRMM, <a name="XERBLA.112"></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">     .. Executable Statements ..
</span><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.LE.0 .OR. N.LE.0 )
     $   RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Check for currently supported options
</span><span class="comment">*</span><span class="comment">
</span>      INFO = 0
      IF( .NOT.<a name="LSAME.124"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( DIRECT, <span class="string">'B'</span> ) ) THEN
         INFO = -3
      ELSE IF( .NOT.<a name="LSAME.126"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( STOREV, <span class="string">'R'</span> ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.130"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="SLARZB.130"></a><a href="slarzb.f.html#SLARZB.1">SLARZB</a>'</span>, -INFO )
         RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( <a name="LSAME.134"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( TRANS, <span class="string">'N'</span> ) ) THEN
         TRANST = <span class="string">'T'</span>
      ELSE
         TRANST = <span class="string">'N'</span>
      END IF
<span class="comment">*</span><span class="comment">
</span>      IF( <a name="LSAME.140"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( SIDE, <span class="string">'L'</span> ) ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Form  H * C  or  H' * C
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:n, 1:k ) = C( 1:k, 1:n )'
</span><span class="comment">*</span><span class="comment">
</span>         DO 10 J = 1, K
            CALL SCOPY( N, C( J, 1 ), LDC, WORK( 1, J ), 1 )
   10    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:n, 1:k ) = W( 1:n, 1:k ) + ...
</span><span class="comment">*</span><span class="comment">                        C( m-l+1:m, 1:n )' * V( 1:k, 1:l )'
</span><span class="comment">*</span><span class="comment">
</span>         IF( L.GT.0 )
     $      CALL SGEMM( <span class="string">'Transpose'</span>, <span class="string">'Transpose'</span>, N, K, L, ONE,
     $                  C( M-L+1, 1 ), LDC, V, LDV, ONE, WORK, LDWORK )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:n, 1:k ) = W( 1:n, 1:k ) * T'  or  W( 1:m, 1:k ) * T
</span><span class="comment">*</span><span class="comment">
</span>         CALL STRMM( <span class="string">'Right'</span>, <span class="string">'Lower'</span>, TRANST, <span class="string">'Non-unit'</span>, N, K, ONE, T,
     $               LDT, WORK, LDWORK )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        C( 1:k, 1:n ) = C( 1:k, 1:n ) - W( 1:n, 1:k )'
</span><span class="comment">*</span><span class="comment">
</span>         DO 30 J = 1, N
            DO 20 I = 1, K
               C( I, J ) = C( I, J ) - WORK( J, I )
   20       CONTINUE
   30    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        C( m-l+1:m, 1:n ) = C( m-l+1:m, 1:n ) - ...
</span><span class="comment">*</span><span class="comment">                            V( 1:k, 1:l )' * W( 1:n, 1:k )'
</span><span class="comment">*</span><span class="comment">
</span>         IF( L.GT.0 )
     $      CALL SGEMM( <span class="string">'Transpose'</span>, <span class="string">'Transpose'</span>, L, N, K, -ONE, V, LDV,
     $                  WORK, LDWORK, ONE, C( M-L+1, 1 ), LDC )
<span class="comment">*</span><span class="comment">
</span>      ELSE IF( <a name="LSAME.177"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( SIDE, <span class="string">'R'</span> ) ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Form  C * H  or  C * H'
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:m, 1:k ) = C( 1:m, 1:k )
</span><span class="comment">*</span><span class="comment">
</span>         DO 40 J = 1, K
            CALL SCOPY( M, C( 1, J ), 1, WORK( 1, J ), 1 )
   40    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:m, 1:k ) = W( 1:m, 1:k ) + ...
</span><span class="comment">*</span><span class="comment">                        C( 1:m, n-l+1:n ) * V( 1:k, 1:l )'
</span><span class="comment">*</span><span class="comment">
</span>         IF( L.GT.0 )
     $      CALL SGEMM( <span class="string">'No transpose'</span>, <span class="string">'Transpose'</span>, M, K, L, ONE,
     $                  C( 1, N-L+1 ), LDC, V, LDV, ONE, WORK, LDWORK )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        W( 1:m, 1:k ) = W( 1:m, 1:k ) * T  or  W( 1:m, 1:k ) * T'
</span><span class="comment">*</span><span class="comment">
</span>         CALL STRMM( <span class="string">'Right'</span>, <span class="string">'Lower'</span>, TRANS, <span class="string">'Non-unit'</span>, M, K, ONE, T,
     $               LDT, WORK, LDWORK )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        C( 1:m, 1:k ) = C( 1:m, 1:k ) - W( 1:m, 1:k )
</span><span class="comment">*</span><span class="comment">
</span>         DO 60 J = 1, K
            DO 50 I = 1, M
               C( I, J ) = C( I, J ) - WORK( I, J )
   50       CONTINUE
   60    CONTINUE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        C( 1:m, n-l+1:n ) = C( 1:m, n-l+1:n ) - ...
</span><span class="comment">*</span><span class="comment">                            W( 1:m, 1:k ) * V( 1:k, 1:l )
</span><span class="comment">*</span><span class="comment">
</span>         IF( L.GT.0 )
     $      CALL SGEMM( <span class="string">'No transpose'</span>, <span class="string">'No transpose'</span>, M, L, K, -ONE,
     $                  WORK, LDWORK, V, LDV, ONE, C( 1, N-L+1 ), LDC )
<span class="comment">*</span><span class="comment">
</span>      END IF
<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="SLARZB.218"></a><a href="slarzb.f.html#SLARZB.1">SLARZB</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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