zpotrf.f.html

来自「famous linear algebra library (LAPACK) p」· HTML 代码 · 共 211 行 · 第 1/2 页

      IF( .NOT.UPPER .AND. .NOT.<a name="LSAME.88"></a><a href="lsame.f.html#LSAME.1">LSAME</a>( UPLO, <span class="string">'L'</span> ) ) THEN
         INFO = -1
      ELSE IF( N.LT.0 ) THEN
         INFO = -2
      ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
         INFO = -4
      END IF
      IF( INFO.NE.0 ) THEN
         CALL <a name="XERBLA.96"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>( <span class="string">'<a name="ZPOTRF.96"></a><a href="zpotrf.f.html#ZPOTRF.1">ZPOTRF</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( N.EQ.0 )
     $   RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     Determine the block size for this environment.
</span><span class="comment">*</span><span class="comment">
</span>      NB = <a name="ILAENV.107"></a><a href="hfy-index.html#ILAENV">ILAENV</a>( 1, <span class="string">'<a name="ZPOTRF.107"></a><a href="zpotrf.f.html#ZPOTRF.1">ZPOTRF</a>'</span>, UPLO, N, -1, -1, -1 )
      IF( NB.LE.1 .OR. NB.GE.N ) 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="ZPOTF2.112"></a><a href="zpotf2.f.html#ZPOTF2.1">ZPOTF2</a>( UPLO, N, A, LDA, INFO )
      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( UPPER ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Compute the Cholesky factorization A = U'*U.
</span><span class="comment">*</span><span class="comment">
</span>            DO 10 J = 1, N, NB
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              Update and factorize the current diagonal block and test
</span><span class="comment">*</span><span class="comment">              for non-positive-definiteness.
</span><span class="comment">*</span><span class="comment">
</span>               JB = MIN( NB, N-J+1 )
               CALL ZHERK( <span class="string">'Upper'</span>, <span class="string">'Conjugate transpose'</span>, JB, J-1,
     $                     -ONE, A( 1, J ), LDA, ONE, A( J, J ), LDA )
               CALL <a name="ZPOTF2.129"></a><a href="zpotf2.f.html#ZPOTF2.1">ZPOTF2</a>( <span class="string">'Upper'</span>, JB, A( J, J ), LDA, INFO )
               IF( INFO.NE.0 )
     $            GO TO 30
               IF( J+JB.LE.N ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Compute the current block row.
</span><span class="comment">*</span><span class="comment">
</span>                  CALL ZGEMM( <span class="string">'Conjugate transpose'</span>, <span class="string">'No transpose'</span>, JB,
     $                        N-J-JB+1, J-1, -CONE, A( 1, J ), LDA,
     $                        A( 1, J+JB ), LDA, CONE, A( J, J+JB ),
     $                        LDA )
                  CALL ZTRSM( <span class="string">'Left'</span>, <span class="string">'Upper'</span>, <span class="string">'Conjugate transpose'</span>,
     $                        <span class="string">'Non-unit'</span>, JB, N-J-JB+1, CONE, A( J, J ),
     $                        LDA, A( J, J+JB ), LDA )
               END IF
   10       CONTINUE
<span class="comment">*</span><span class="comment">
</span>         ELSE
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">           Compute the Cholesky factorization A = L*L'.
</span><span class="comment">*</span><span class="comment">
</span>            DO 20 J = 1, N, NB
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">              Update and factorize the current diagonal block and test
</span><span class="comment">*</span><span class="comment">              for non-positive-definiteness.
</span><span class="comment">*</span><span class="comment">
</span>               JB = MIN( NB, N-J+1 )
               CALL ZHERK( <span class="string">'Lower'</span>, <span class="string">'No transpose'</span>, JB, J-1, -ONE,
     $                     A( J, 1 ), LDA, ONE, A( J, J ), LDA )
               CALL <a name="ZPOTF2.158"></a><a href="zpotf2.f.html#ZPOTF2.1">ZPOTF2</a>( <span class="string">'Lower'</span>, JB, A( J, J ), LDA, INFO )
               IF( INFO.NE.0 )
     $            GO TO 30
               IF( J+JB.LE.N ) THEN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">                 Compute the current block column.
</span><span class="comment">*</span><span class="comment">
</span>                  CALL ZGEMM( <span class="string">'No transpose'</span>, <span class="string">'Conjugate transpose'</span>,
     $                        N-J-JB+1, JB, J-1, -CONE, A( J+JB, 1 ),
     $                        LDA, A( J, 1 ), LDA, CONE, A( J+JB, J ),
     $                        LDA )
                  CALL ZTRSM( <span class="string">'Right'</span>, <span class="string">'Lower'</span>, <span class="string">'Conjugate transpose'</span>,
     $                        <span class="string">'Non-unit'</span>, N-J-JB+1, JB, CONE, A( J, J ),
     $                        LDA, A( J+JB, J ), LDA )
               END IF
   20       CONTINUE
         END IF
      END IF
      GO TO 40
<span class="comment">*</span><span class="comment">
</span>   30 CONTINUE
      INFO = INFO + J - 1
<span class="comment">*</span><span class="comment">
</span>   40 CONTINUE
      RETURN
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment">     End of <a name="ZPOTRF.184"></a><a href="zpotrf.f.html#ZPOTRF.1">ZPOTRF</a>
</span><span class="comment">*</span><span class="comment">
</span>      END

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