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author | julie <julielangou@users.noreply.github.com> | 2011-10-06 06:53:11 +0000 |
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committer | julie <julielangou@users.noreply.github.com> | 2011-10-06 06:53:11 +0000 |
commit | e1d39294aee16fa6db9ba079b14442358217db71 (patch) | |
tree | 30e5aa04c1f6596991fda5334f63dfb9b8027849 /SRC/dlasv2.f | |
parent | 5fe0466a14e395641f4f8a300ecc9dcb8058081b (diff) | |
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Integrating Doxygen in comments
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-rw-r--r-- | SRC/dlasv2.f | 179 |
1 files changed, 123 insertions, 56 deletions
diff --git a/SRC/dlasv2.f b/SRC/dlasv2.f index dd3b7e98..4dd6eee1 100644 --- a/SRC/dlasv2.f +++ b/SRC/dlasv2.f @@ -1,78 +1,145 @@ - SUBROUTINE DLASV2( F, G, H, SSMIN, SSMAX, SNR, CSR, SNL, CSL ) +*> \brief \b DLASV2 * -* -- LAPACK auxiliary routine (version 3.2) -- -* -- LAPACK is a software package provided by Univ. of Tennessee, -- -* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- -* November 2006 +* =========== DOCUMENTATION =========== * -* .. Scalar Arguments .. - DOUBLE PRECISION CSL, CSR, F, G, H, SNL, SNR, SSMAX, SSMIN -* .. +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +* Definition +* ========== * +* SUBROUTINE DLASV2( F, G, H, SSMIN, SSMAX, SNR, CSR, SNL, CSL ) +* +* .. Scalar Arguments .. +* DOUBLE PRECISION CSL, CSR, F, G, H, SNL, SNR, SSMAX, SSMIN +* .. +* * Purpose * ======= * -* DLASV2 computes the singular value decomposition of a 2-by-2 -* triangular matrix -* [ F G ] -* [ 0 H ]. -* On return, abs(SSMAX) is the larger singular value, abs(SSMIN) is the -* smaller singular value, and (CSL,SNL) and (CSR,SNR) are the left and -* right singular vectors for abs(SSMAX), giving the decomposition -* -* [ CSL SNL ] [ F G ] [ CSR -SNR ] = [ SSMAX 0 ] -* [-SNL CSL ] [ 0 H ] [ SNR CSR ] [ 0 SSMIN ]. +*>\details \b Purpose: +*>\verbatim +*> +*> DLASV2 computes the singular value decomposition of a 2-by-2 +*> triangular matrix +*> [ F G ] +*> [ 0 H ]. +*> On return, abs(SSMAX) is the larger singular value, abs(SSMIN) is the +*> smaller singular value, and (CSL,SNL) and (CSR,SNR) are the left and +*> right singular vectors for abs(SSMAX), giving the decomposition +*> +*> [ CSL SNL ] [ F G ] [ CSR -SNR ] = [ SSMAX 0 ] +*> [-SNL CSL ] [ 0 H ] [ SNR CSR ] [ 0 SSMIN ]. +*> +*>\endverbatim * * Arguments * ========= * -* F (input) DOUBLE PRECISION -* The (1,1) element of the 2-by-2 matrix. -* -* G (input) DOUBLE PRECISION -* The (1,2) element of the 2-by-2 matrix. -* -* H (input) DOUBLE PRECISION -* The (2,2) element of the 2-by-2 matrix. -* -* SSMIN (output) DOUBLE PRECISION -* abs(SSMIN) is the smaller singular value. -* -* SSMAX (output) DOUBLE PRECISION -* abs(SSMAX) is the larger singular value. +*> \param[in] F +*> \verbatim +*> F is DOUBLE PRECISION +*> The (1,1) element of the 2-by-2 matrix. +*> \endverbatim +*> +*> \param[in] G +*> \verbatim +*> G is DOUBLE PRECISION +*> The (1,2) element of the 2-by-2 matrix. +*> \endverbatim +*> +*> \param[in] H +*> \verbatim +*> H is DOUBLE PRECISION +*> The (2,2) element of the 2-by-2 matrix. +*> \endverbatim +*> +*> \param[out] SSMIN +*> \verbatim +*> SSMIN is DOUBLE PRECISION +*> abs(SSMIN) is the smaller singular value. +*> \endverbatim +*> +*> \param[out] SSMAX +*> \verbatim +*> SSMAX is DOUBLE PRECISION +*> abs(SSMAX) is the larger singular value. +*> \endverbatim +*> +*> \param[out] SNL +*> \verbatim +*> SNL is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[out] CSL +*> \verbatim +*> CSL is DOUBLE PRECISION +*> The vector (CSL, SNL) is a unit left singular vector for the +*> singular value abs(SSMAX). +*> \endverbatim +*> +*> \param[out] SNR +*> \verbatim +*> SNR is DOUBLE PRECISION +*> \endverbatim +*> +*> \param[out] CSR +*> \verbatim +*> CSR is DOUBLE PRECISION +*> The vector (CSR, SNR) is a unit right singular vector for the +*> singular value abs(SSMAX). +*> \endverbatim +*> +* +* Authors +* ======= * -* SNL (output) DOUBLE PRECISION +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. * -* CSL (output) DOUBLE PRECISION -* The vector (CSL, SNL) is a unit left singular vector for the -* singular value abs(SSMAX). +*> \date November 2011 * -* SNR (output) DOUBLE PRECISION +*> \ingroup auxOTHERauxiliary * -* CSR (output) DOUBLE PRECISION -* The vector (CSR, SNR) is a unit right singular vector for the -* singular value abs(SSMAX). * * Further Details * =============== +*>\details \b Further \b Details +*> \verbatim +*> +*> Any input parameter may be aliased with any output parameter. +*> +*> Barring over/underflow and assuming a guard digit in subtraction, all +*> output quantities are correct to within a few units in the last +*> place (ulps). +*> +*> In IEEE arithmetic, the code works correctly if one matrix element is +*> infinite. +*> +*> Overflow will not occur unless the largest singular value itself +*> overflows or is within a few ulps of overflow. (On machines with +*> partial overflow, like the Cray, overflow may occur if the largest +*> singular value is within a factor of 2 of overflow.) +*> +*> Underflow is harmless if underflow is gradual. Otherwise, results +*> may correspond to a matrix modified by perturbations of size near +*> the underflow threshold. +*> +*> \endverbatim +*> +* ===================================================================== + SUBROUTINE DLASV2( F, G, H, SSMIN, SSMAX, SNR, CSR, SNL, CSL ) * -* Any input parameter may be aliased with any output parameter. -* -* Barring over/underflow and assuming a guard digit in subtraction, all -* output quantities are correct to within a few units in the last -* place (ulps). -* -* In IEEE arithmetic, the code works correctly if one matrix element is -* infinite. -* -* Overflow will not occur unless the largest singular value itself -* overflows or is within a few ulps of overflow. (On machines with -* partial overflow, like the Cray, overflow may occur if the largest -* singular value is within a factor of 2 of overflow.) +* -- LAPACK auxiliary routine (version 3.2) -- +* -- LAPACK is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2011 * -* Underflow is harmless if underflow is gradual. Otherwise, results -* may correspond to a matrix modified by perturbations of size near -* the underflow threshold. +* .. Scalar Arguments .. + DOUBLE PRECISION CSL, CSR, F, G, H, SNL, SNR, SSMAX, SSMIN +* .. * * ===================================================================== * |