dsymm.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 319 行 · 第 1/2 页

</span><span class="comment">*</span><span class="comment">     .. Intrinsic Functions ..
</span>      INTRINSIC MAX
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Local Scalars ..
</span>      DOUBLE PRECISION TEMP1,TEMP2
      INTEGER I,INFO,J,K,NROWA
      LOGICAL UPPER
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">     .. Parameters ..
</span>      DOUBLE PRECISION ONE,ZERO
      PARAMETER (ONE=1.0D+0,ZERO=0.0D+0)
<span class="comment">*</span><span class="comment">     ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Set NROWA as the number of rows of A.
</span><span class="comment">*</span><span class="comment">
</span>      IF (<a name="LSAME.157"></a><a href="lsame.f.html#LSAME.1">LSAME</a>(SIDE,<span class="string">'L'</span>)) THEN
          NROWA = M
      ELSE
          NROWA = N
      END IF
      UPPER = <a name="LSAME.162"></a><a href="lsame.f.html#LSAME.1">LSAME</a>(UPLO,<span class="string">'U'</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>      INFO = 0
      IF ((.NOT.<a name="LSAME.167"></a><a href="lsame.f.html#LSAME.1">LSAME</a>(SIDE,<span class="string">'L'</span>)) .AND. (.NOT.<a name="LSAME.167"></a><a href="lsame.f.html#LSAME.1">LSAME</a>(SIDE,<span class="string">'R'</span>))) THEN
          INFO = 1
      ELSE IF ((.NOT.UPPER) .AND. (.NOT.<a name="LSAME.169"></a><a href="lsame.f.html#LSAME.1">LSAME</a>(UPLO,<span class="string">'L'</span>))) THEN
          INFO = 2
      ELSE IF (M.LT.0) THEN
          INFO = 3
      ELSE IF (N.LT.0) THEN
          INFO = 4
      ELSE IF (LDA.LT.MAX(1,NROWA)) THEN
          INFO = 7
      ELSE IF (LDB.LT.MAX(1,M)) THEN
          INFO = 9
      ELSE IF (LDC.LT.MAX(1,M)) THEN
          INFO = 12
      END IF
      IF (INFO.NE.0) THEN
          CALL <a name="XERBLA.183"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>(<span class="string">'<a name="DSYMM.183"></a><a href="dsymm.f.html#DSYMM.1">DSYMM</a> '</span>,INFO)
          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) .OR.
     +    ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     And when  alpha.eq.zero.
</span><span class="comment">*</span><span class="comment">
</span>      IF (ALPHA.EQ.ZERO) THEN
          IF (BETA.EQ.ZERO) THEN
              DO 20 J = 1,N
                  DO 10 I = 1,M
                      C(I,J) = ZERO
   10             CONTINUE
   20         CONTINUE
          ELSE
              DO 40 J = 1,N
                  DO 30 I = 1,M
                      C(I,J) = BETA*C(I,J)
   30             CONTINUE
   40         CONTINUE
          END IF
          RETURN
      END IF
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Start the operations.
</span><span class="comment">*</span><span class="comment">
</span>      IF (<a name="LSAME.213"></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  C := alpha*A*B + beta*C.
</span><span class="comment">*</span><span class="comment">
</span>          IF (UPPER) THEN
              DO 70 J = 1,N
                  DO 60 I = 1,M
                      TEMP1 = ALPHA*B(I,J)
                      TEMP2 = ZERO
                      DO 50 K = 1,I - 1
                          C(K,J) = C(K,J) + TEMP1*A(K,I)
                          TEMP2 = TEMP2 + B(K,J)*A(K,I)
   50                 CONTINUE
                      IF (BETA.EQ.ZERO) THEN
                          C(I,J) = TEMP1*A(I,I) + ALPHA*TEMP2
                      ELSE
                          C(I,J) = BETA*C(I,J) + TEMP1*A(I,I) +
     +                             ALPHA*TEMP2
                      END IF
   60             CONTINUE
   70         CONTINUE
          ELSE
              DO 100 J = 1,N
                  DO 90 I = M,1,-1
                      TEMP1 = ALPHA*B(I,J)
                      TEMP2 = ZERO
                      DO 80 K = I + 1,M
                          C(K,J) = C(K,J) + TEMP1*A(K,I)
                          TEMP2 = TEMP2 + B(K,J)*A(K,I)
   80                 CONTINUE
                      IF (BETA.EQ.ZERO) THEN
                          C(I,J) = TEMP1*A(I,I) + ALPHA*TEMP2
                      ELSE
                          C(I,J) = BETA*C(I,J) + TEMP1*A(I,I) +
     +                             ALPHA*TEMP2
                      END IF
   90             CONTINUE
  100         CONTINUE
          END IF
      ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">        Form  C := alpha*B*A + beta*C.
</span><span class="comment">*</span><span class="comment">
</span>          DO 170 J = 1,N
              TEMP1 = ALPHA*A(J,J)
              IF (BETA.EQ.ZERO) THEN
                  DO 110 I = 1,M
                      C(I,J) = TEMP1*B(I,J)
  110             CONTINUE
              ELSE
                  DO 120 I = 1,M
                      C(I,J) = BETA*C(I,J) + TEMP1*B(I,J)
  120             CONTINUE
              END IF
              DO 140 K = 1,J - 1
                  IF (UPPER) THEN
                      TEMP1 = ALPHA*A(K,J)
                  ELSE
                      TEMP1 = ALPHA*A(J,K)
                  END IF
                  DO 130 I = 1,M
                      C(I,J) = C(I,J) + TEMP1*B(I,K)
  130             CONTINUE
  140         CONTINUE
              DO 160 K = J + 1,N
                  IF (UPPER) THEN
                      TEMP1 = ALPHA*A(J,K)
                  ELSE
                      TEMP1 = ALPHA*A(K,J)
                  END IF
                  DO 150 I = 1,M
                      C(I,J) = C(I,J) + TEMP1*B(I,K)
  150             CONTINUE
  160         CONTINUE
  170     CONTINUE
      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="DSYMM.292"></a><a href="dsymm.f.html#DSYMM.1">DSYMM</a> .
</span><span class="comment">*</span><span class="comment">
</span>      END

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