version 1.3, 2010/08/13 21:03:47
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version 1.6, 2011/11/21 22:19:30
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SUBROUTINE DLA_LIN_BERR ( N, NZ, NRHS, RES, AYB, BERR ) |
*> \brief \b DLA_LIN_BERR |
* |
* |
* -- LAPACK routine (version 3.2.2) -- |
* =========== DOCUMENTATION =========== |
* -- Contributed by James Demmel, Deaglan Halligan, Yozo Hida and -- |
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* -- Jason Riedy of Univ. of California Berkeley. -- |
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* -- June 2010 -- |
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* |
* |
* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
* Online html documentation available at |
* -- Univ. of California Berkeley and NAG Ltd. -- |
* http://www.netlib.org/lapack/explore-html/ |
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* |
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*> \htmlonly |
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*> Download DLA_LIN_BERR + dependencies |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dla_lin_berr.f"> |
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*> [TGZ]</a> |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dla_lin_berr.f"> |
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*> [ZIP]</a> |
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dla_lin_berr.f"> |
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*> [TXT]</a> |
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*> \endhtmlonly |
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* |
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* Definition: |
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* =========== |
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* |
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* SUBROUTINE DLA_LIN_BERR ( N, NZ, NRHS, RES, AYB, BERR ) |
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* |
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* .. Scalar Arguments .. |
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* INTEGER N, NZ, NRHS |
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* .. |
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* .. Array Arguments .. |
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* DOUBLE PRECISION AYB( N, NRHS ), BERR( NRHS ) |
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* DOUBLE PRECISION RES( N, NRHS ) |
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* .. |
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* |
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* |
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*> \par Purpose: |
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* ============= |
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*> |
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*> \verbatim |
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*> |
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*> DLA_LIN_BERR computes component-wise relative backward error from |
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*> the formula |
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*> max(i) ( abs(R(i)) / ( abs(op(A_s))*abs(Y) + abs(B_s) )(i) ) |
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*> where abs(Z) is the component-wise absolute value of the matrix |
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*> or vector Z. |
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*> \endverbatim |
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* |
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* Arguments: |
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* ========== |
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* |
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*> \param[in] N |
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*> \verbatim |
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*> N is INTEGER |
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*> The number of linear equations, i.e., the order of the |
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*> matrix A. N >= 0. |
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*> \endverbatim |
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*> |
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*> \param[in] NZ |
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*> \verbatim |
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*> NZ is INTEGER |
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*> We add (NZ+1)*SLAMCH( 'Safe minimum' ) to R(i) in the numerator to |
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*> guard against spuriously zero residuals. Default value is N. |
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*> \endverbatim |
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*> |
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*> \param[in] NRHS |
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*> \verbatim |
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*> NRHS is INTEGER |
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*> The number of right hand sides, i.e., the number of columns |
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*> of the matrices AYB, RES, and BERR. NRHS >= 0. |
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*> \endverbatim |
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*> |
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*> \param[in] RES |
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*> \verbatim |
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*> RES is DOUBLE PRECISION array, dimension (N,NRHS) |
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*> The residual matrix, i.e., the matrix R in the relative backward |
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*> error formula above. |
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*> \endverbatim |
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*> |
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*> \param[in] AYB |
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*> \verbatim |
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*> AYB is DOUBLE PRECISION array, dimension (N, NRHS) |
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*> The denominator in the relative backward error formula above, i.e., |
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*> the matrix abs(op(A_s))*abs(Y) + abs(B_s). The matrices A, Y, and B |
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*> are from iterative refinement (see dla_gerfsx_extended.f). |
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*> \endverbatim |
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*> |
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*> \param[out] BERR |
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*> \verbatim |
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*> BERR is DOUBLE PRECISION array, dimension (NRHS) |
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*> The component-wise relative backward error from the formula above. |
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*> \endverbatim |
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* |
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* Authors: |
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* ======== |
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* |
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*> \author Univ. of Tennessee |
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*> \author Univ. of California Berkeley |
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*> \author Univ. of Colorado Denver |
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*> \author NAG Ltd. |
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* |
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*> \date November 2011 |
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* |
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*> \ingroup doubleOTHERcomputational |
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* |
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* ===================================================================== |
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SUBROUTINE DLA_LIN_BERR ( N, NZ, NRHS, RES, AYB, BERR ) |
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* |
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* -- LAPACK computational routine (version 3.4.0) -- |
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* -- LAPACK is a software package provided by Univ. of Tennessee, -- |
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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* November 2011 |
* |
* |
IMPLICIT NONE |
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* .. |
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* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER N, NZ, NRHS |
INTEGER N, NZ, NRHS |
* .. |
* .. |
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DOUBLE PRECISION RES( N, NRHS ) |
DOUBLE PRECISION RES( N, NRHS ) |
* .. |
* .. |
* |
* |
* Purpose |
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* ======= |
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* |
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* DLA_LIN_BERR computes component-wise relative backward error from |
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* the formula |
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* max(i) ( abs(R(i)) / ( abs(op(A_s))*abs(Y) + abs(B_s) )(i) ) |
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* where abs(Z) is the component-wise absolute value of the matrix |
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* or vector Z. |
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* |
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* Arguments |
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* ========== |
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* |
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* N (input) INTEGER |
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* The number of linear equations, i.e., the order of the |
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* matrix A. N >= 0. |
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* |
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* NZ (input) INTEGER |
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* We add (NZ+1)*SLAMCH( 'Safe minimum' ) to R(i) in the numerator to |
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* guard against spuriously zero residuals. Default value is N. |
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* |
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* NRHS (input) INTEGER |
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* The number of right hand sides, i.e., the number of columns |
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* of the matrices AYB, RES, and BERR. NRHS >= 0. |
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* |
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* RES (input) DOUBLE PRECISION array, dimension (N,NRHS) |
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* The residual matrix, i.e., the matrix R in the relative backward |
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* error formula above. |
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* |
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* AYB (input) DOUBLE PRECISION array, dimension (N, NRHS) |
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* The denominator in the relative backward error formula above, i.e., |
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* the matrix abs(op(A_s))*abs(Y) + abs(B_s). The matrices A, Y, and B |
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* are from iterative refinement (see dla_gerfsx_extended.f). |
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* |
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* BERR (output) DOUBLE PRECISION array, dimension (NRHS) |
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* The component-wise relative backward error from the formula above. |
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* |
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* ===================================================================== |
* ===================================================================== |
* |
* |
* .. Local Scalars .. |
* .. Local Scalars .. |