dtrsyl.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 938 行 · 第 1/4 页

HTML
938 行
字号
1234
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( K1-1, A( 1, K2 ), 1, C( 1, L2 ), 1 )
                  SUMR = DDOT( N-L2, C( K2, MIN( L2+1, N ) ), LDC,
     $                   B( L2, MIN( L2+1, N ) ), LDB )
                  VEC( 2, 2 ) = C( K2, L2 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  CALL <a name="DLASY2.693"></a><a href="dlasy2.f.html#DLASY2.1">DLASY2</a>( .TRUE., .TRUE., ISGN, 2, 2, A( K1, K1 ),
     $                         LDA, B( L1, L1 ), LDB, VEC, 2, SCALOC, X,
     $                         2, XNORM, IERR )
                  IF( IERR.NE.0 )
     $               INFO = 1
<span class="comment">*</span><span class="comment">
</span>                  IF( SCALOC.NE.ONE ) THEN
                     DO 160 J = 1, N
                        CALL DSCAL( M, SCALOC, C( 1, J ), 1 )
  160                CONTINUE
                     SCALE = SCALE*SCALOC
                  END IF
                  C( K1, L1 ) = X( 1, 1 )
                  C( K1, L2 ) = X( 1, 2 )
                  C( K2, L1 ) = X( 2, 1 )
                  C( K2, L2 ) = X( 2, 2 )
               END IF
<span class="comment">*</span><span class="comment">
</span>  170       CONTINUE
  180    CONTINUE
<span class="comment">*</span><span class="comment">
</span>      ELSE IF( NOTRNA .AND. .NOT.NOTRNB ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Solve    A*X + ISGN*X*B' = scale*C.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        The (K,L)th block of X is determined starting from
</span><span class="comment">*</span><span class="comment">        bottom-right corner column by column by
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">            A(K,K)*X(K,L) + ISGN*X(K,L)*B(L,L)' = C(K,L) - R(K,L)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Where
</span><span class="comment">*</span><span class="comment">                      M                          N
</span><span class="comment">*</span><span class="comment">            R(K,L) = SUM [A(K,I)*X(I,L)] + ISGN*SUM [X(K,J)*B(L,J)'].
</span><span class="comment">*</span><span class="comment">                    I=K+1                      J=L+1
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Start column loop (index = L)
</span><span class="comment">*</span><span class="comment">        L1 (L2): column index of the first (last) row of X(K,L)
</span><span class="comment">*</span><span class="comment">
</span>         LNEXT = N
         DO 240 L = N, 1, -1
            IF( L.GT.LNEXT )
     $         GO TO 240
            IF( L.EQ.1 ) THEN
               L1 = L
               L2 = L
            ELSE
               IF( B( L, L-1 ).NE.ZERO ) THEN
                  L1 = L - 1
                  L2 = L
                  LNEXT = L - 2
               ELSE
                  L1 = L
                  L2 = L
                  LNEXT = L - 1
               END IF
            END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Start row loop (index = K)
</span><span class="comment">*</span><span class="comment">           K1 (K2): row index of the first (last) row of X(K,L)
</span><span class="comment">*</span><span class="comment">
</span>            KNEXT = M
            DO 230 K = M, 1, -1
               IF( K.GT.KNEXT )
     $            GO TO 230
               IF( K.EQ.1 ) THEN
                  K1 = K
                  K2 = K
               ELSE
                  IF( A( K, K-1 ).NE.ZERO ) THEN
                     K1 = K - 1
                     K2 = K
                     KNEXT = K - 2
                  ELSE
                     K1 = K
                     K2 = K
                     KNEXT = K - 1
                  END IF
               END IF
<span class="comment">*</span><span class="comment">
</span>               IF( L1.EQ.L2 .AND. K1.EQ.K2 ) THEN
                  SUML = DDOT( M-K1, A( K1, MIN( K1+1, M ) ), LDA,
     $                   C( MIN( K1+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L1, C( K1, MIN( L1+1, N ) ), LDC,
     $                   B( L1, MIN( L1+1, N ) ), LDB )
                  VEC( 1, 1 ) = C( K1, L1 ) - ( SUML+SGN*SUMR )
                  SCALOC = ONE
<span class="comment">*</span><span class="comment">
</span>                  A11 = A( K1, K1 ) + SGN*B( L1, L1 )
                  DA11 = ABS( A11 )
                  IF( DA11.LE.SMIN ) THEN
                     A11 = SMIN
                     DA11 = SMIN
                     INFO = 1
                  END IF
                  DB = ABS( VEC( 1, 1 ) )
                  IF( DA11.LT.ONE .AND. DB.GT.ONE ) THEN
                     IF( DB.GT.BIGNUM*DA11 )
     $                  SCALOC = ONE / DB
                  END IF
                  X( 1, 1 ) = ( VEC( 1, 1 )*SCALOC ) / A11
<span class="comment">*</span><span class="comment">
</span>                  IF( SCALOC.NE.ONE ) THEN
                     DO 190 J = 1, N
                        CALL DSCAL( M, SCALOC, C( 1, J ), 1 )
  190                CONTINUE
                     SCALE = SCALE*SCALOC
                  END IF
                  C( K1, L1 ) = X( 1, 1 )
<span class="comment">*</span><span class="comment">
</span>               ELSE IF( L1.EQ.L2 .AND. K1.NE.K2 ) THEN
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K1, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L2, C( K1, MIN( L2+1, N ) ), LDC,
     $                   B( L1, MIN( L2+1, N ) ), LDB )
                  VEC( 1, 1 ) = C( K1, L1 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K2, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L2, C( K2, MIN( L2+1, N ) ), LDC,
     $                   B( L1, MIN( L2+1, N ) ), LDB )
                  VEC( 2, 1 ) = C( K2, L1 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  CALL <a name="DLALN2.816"></a><a href="dlaln2.f.html#DLALN2.1">DLALN2</a>( .FALSE., 2, 1, SMIN, ONE, A( K1, K1 ),
     $                         LDA, ONE, ONE, VEC, 2, -SGN*B( L1, L1 ),
     $                         ZERO, X, 2, SCALOC, XNORM, IERR )
                  IF( IERR.NE.0 )
     $               INFO = 1
<span class="comment">*</span><span class="comment">
</span>                  IF( SCALOC.NE.ONE ) THEN
                     DO 200 J = 1, N
                        CALL DSCAL( M, SCALOC, C( 1, J ), 1 )
  200                CONTINUE
                     SCALE = SCALE*SCALOC
                  END IF
                  C( K1, L1 ) = X( 1, 1 )
                  C( K2, L1 ) = X( 2, 1 )
<span class="comment">*</span><span class="comment">
</span>               ELSE IF( L1.NE.L2 .AND. K1.EQ.K2 ) THEN
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K1, A( K1, MIN( K1+1, M ) ), LDA,
     $                   C( MIN( K1+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L2, C( K1, MIN( L2+1, N ) ), LDC,
     $                   B( L1, MIN( L2+1, N ) ), LDB )
                  VEC( 1, 1 ) = SGN*( C( K1, L1 )-( SUML+SGN*SUMR ) )
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K1, A( K1, MIN( K1+1, M ) ), LDA,
     $                   C( MIN( K1+1, M ), L2 ), 1 )
                  SUMR = DDOT( N-L2, C( K1, MIN( L2+1, N ) ), LDC,
     $                   B( L2, MIN( L2+1, N ) ), LDB )
                  VEC( 2, 1 ) = SGN*( C( K1, L2 )-( SUML+SGN*SUMR ) )
<span class="comment">*</span><span class="comment">
</span>                  CALL <a name="DLALN2.845"></a><a href="dlaln2.f.html#DLALN2.1">DLALN2</a>( .FALSE., 2, 1, SMIN, ONE, B( L1, L1 ),
     $                         LDB, ONE, ONE, VEC, 2, -SGN*A( K1, K1 ),
     $                         ZERO, X, 2, SCALOC, XNORM, IERR )
                  IF( IERR.NE.0 )
     $               INFO = 1
<span class="comment">*</span><span class="comment">
</span>                  IF( SCALOC.NE.ONE ) THEN
                     DO 210 J = 1, N
                        CALL DSCAL( M, SCALOC, C( 1, J ), 1 )
  210                CONTINUE
                     SCALE = SCALE*SCALOC
                  END IF
                  C( K1, L1 ) = X( 1, 1 )
                  C( K1, L2 ) = X( 2, 1 )
<span class="comment">*</span><span class="comment">
</span>               ELSE IF( L1.NE.L2 .AND. K1.NE.K2 ) THEN
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K1, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L2, C( K1, MIN( L2+1, N ) ), LDC,
     $                   B( L1, MIN( L2+1, N ) ), LDB )
                  VEC( 1, 1 ) = C( K1, L1 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K1, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L2 ), 1 )
                  SUMR = DDOT( N-L2, C( K1, MIN( L2+1, N ) ), LDC,
     $                   B( L2, MIN( L2+1, N ) ), LDB )
                  VEC( 1, 2 ) = C( K1, L2 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K2, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L1 ), 1 )
                  SUMR = DDOT( N-L2, C( K2, MIN( L2+1, N ) ), LDC,
     $                   B( L1, MIN( L2+1, N ) ), LDB )
                  VEC( 2, 1 ) = C( K2, L1 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  SUML = DDOT( M-K2, A( K2, MIN( K2+1, M ) ), LDA,
     $                   C( MIN( K2+1, M ), L2 ), 1 )
                  SUMR = DDOT( N-L2, C( K2, MIN( L2+1, N ) ), LDC,
     $                   B( L2, MIN( L2+1, N ) ), LDB )
                  VEC( 2, 2 ) = C( K2, L2 ) - ( SUML+SGN*SUMR )
<span class="comment">*</span><span class="comment">
</span>                  CALL <a name="DLASY2.886"></a><a href="dlasy2.f.html#DLASY2.1">DLASY2</a>( .FALSE., .TRUE., ISGN, 2, 2, A( K1, K1 ),
     $                         LDA, B( L1, L1 ), LDB, VEC, 2, SCALOC, X,
     $                         2, XNORM, IERR )
                  IF( IERR.NE.0 )
     $               INFO = 1
<span class="comment">*</span><span class="comment">
</span>                  IF( SCALOC.NE.ONE ) THEN
                     DO 220 J = 1, N
                        CALL DSCAL( M, SCALOC, C( 1, J ), 1 )
  220                CONTINUE
                     SCALE = SCALE*SCALOC
                  END IF
                  C( K1, L1 ) = X( 1, 1 )
                  C( K1, L2 ) = X( 1, 2 )
                  C( K2, L1 ) = X( 2, 1 )
                  C( K2, L2 ) = X( 2, 2 )
               END IF
<span class="comment">*</span><span class="comment">
</span>  230       CONTINUE
  240    CONTINUE
<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="DTRSYL.911"></a><a href="dtrsyl.f.html#DTRSYL.1">DTRSYL</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

</pre>

 </body>
</html>
1234

dtrsyl.f.html - 源码说明

本页面展示了「famous linear algebra library (LAPACK) ports to windows」中的 dtrsyl.f.html 源码文件，采用 HTML 编程语言编写，共 938 行代码。您可以在线阅读完整代码内容，也可以返回资源详情页下载完整源码包进行本地学习和开发。

虫虫下载站收录了大量与algebra相关的技术资源，包括源代码、技术文档、电路图等，是电子工程师和嵌入式开发者的专业学习平台。

⌨️ 快捷键说明

复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?