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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/dgttrf.f | |
parent | 5fe0466a14e395641f4f8a300ecc9dcb8058081b (diff) | |
download | lapack-e1d39294aee16fa6db9ba079b14442358217db71.tar.gz lapack-e1d39294aee16fa6db9ba079b14442358217db71.tar.bz2 lapack-e1d39294aee16fa6db9ba079b14442358217db71.zip |
Integrating Doxygen in comments
Diffstat (limited to 'SRC/dgttrf.f')
-rw-r--r-- | SRC/dgttrf.f | 177 |
1 files changed, 120 insertions, 57 deletions
diff --git a/SRC/dgttrf.f b/SRC/dgttrf.f index d12df005..d2dee1ce 100644 --- a/SRC/dgttrf.f +++ b/SRC/dgttrf.f @@ -1,73 +1,136 @@ - SUBROUTINE DGTTRF( N, DL, D, DU, DU2, IPIV, INFO ) -* -* -- LAPACK 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 -* -* .. Scalar Arguments .. - INTEGER INFO, N -* .. -* .. Array Arguments .. - INTEGER IPIV( * ) - DOUBLE PRECISION D( * ), DL( * ), DU( * ), DU2( * ) -* .. -* +*> \brief \b DGTTRF +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +* Definition +* ========== +* +* SUBROUTINE DGTTRF( N, DL, D, DU, DU2, IPIV, INFO ) +* +* .. Scalar Arguments .. +* INTEGER INFO, N +* .. +* .. Array Arguments .. +* INTEGER IPIV( * ) +* DOUBLE PRECISION D( * ), DL( * ), DU( * ), DU2( * ) +* .. +* * Purpose * ======= * -* DGTTRF computes an LU factorization of a real tridiagonal matrix A -* using elimination with partial pivoting and row interchanges. -* -* The factorization has the form -* A = L * U -* where L is a product of permutation and unit lower bidiagonal -* matrices and U is upper triangular with nonzeros in only the main -* diagonal and first two superdiagonals. +*>\details \b Purpose: +*>\verbatim +*> +*> DGTTRF computes an LU factorization of a real tridiagonal matrix A +*> using elimination with partial pivoting and row interchanges. +*> +*> The factorization has the form +*> A = L * U +*> where L is a product of permutation and unit lower bidiagonal +*> matrices and U is upper triangular with nonzeros in only the main +*> diagonal and first two superdiagonals. +*> +*>\endverbatim * * Arguments * ========= * -* N (input) INTEGER -* The order of the matrix A. -* -* DL (input/output) DOUBLE PRECISION array, dimension (N-1) -* On entry, DL must contain the (n-1) sub-diagonal elements of -* A. -* -* On exit, DL is overwritten by the (n-1) multipliers that -* define the matrix L from the LU factorization of A. -* -* D (input/output) DOUBLE PRECISION array, dimension (N) -* On entry, D must contain the diagonal elements of A. +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> The order of the matrix A. +*> \endverbatim +*> +*> \param[in,out] DL +*> \verbatim +*> DL is DOUBLE PRECISION array, dimension (N-1) +*> On entry, DL must contain the (n-1) sub-diagonal elements of +*> A. +*> \endverbatim +*> \verbatim +*> On exit, DL is overwritten by the (n-1) multipliers that +*> define the matrix L from the LU factorization of A. +*> \endverbatim +*> +*> \param[in,out] D +*> \verbatim +*> D is DOUBLE PRECISION array, dimension (N) +*> On entry, D must contain the diagonal elements of A. +*> \endverbatim +*> \verbatim +*> On exit, D is overwritten by the n diagonal elements of the +*> upper triangular matrix U from the LU factorization of A. +*> \endverbatim +*> +*> \param[in,out] DU +*> \verbatim +*> DU is DOUBLE PRECISION array, dimension (N-1) +*> On entry, DU must contain the (n-1) super-diagonal elements +*> of A. +*> \endverbatim +*> \verbatim +*> On exit, DU is overwritten by the (n-1) elements of the first +*> super-diagonal of U. +*> \endverbatim +*> +*> \param[out] DU2 +*> \verbatim +*> DU2 is DOUBLE PRECISION array, dimension (N-2) +*> On exit, DU2 is overwritten by the (n-2) elements of the +*> second super-diagonal of U. +*> \endverbatim +*> +*> \param[out] IPIV +*> \verbatim +*> IPIV is INTEGER array, dimension (N) +*> The pivot indices; for 1 <= i <= n, row i of the matrix was +*> interchanged with row IPIV(i). IPIV(i) will always be either +*> i or i+1; IPIV(i) = i indicates a row interchange was not +*> required. +*> \endverbatim +*> +*> \param[out] INFO +*> \verbatim +*> INFO is INTEGER +*> = 0: successful exit +*> < 0: if INFO = -k, the k-th argument had an illegal value +*> > 0: if INFO = k, U(k,k) is exactly zero. The factorization +*> has been completed, but the factor U is exactly +*> singular, and division by zero will occur if it is used +*> to solve a system of equations. +*> \endverbatim +*> +* +* Authors +* ======= * -* On exit, D is overwritten by the n diagonal elements of the -* upper triangular matrix U from the LU factorization of A. +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. * -* DU (input/output) DOUBLE PRECISION array, dimension (N-1) -* On entry, DU must contain the (n-1) super-diagonal elements -* of A. +*> \date November 2011 * -* On exit, DU is overwritten by the (n-1) elements of the first -* super-diagonal of U. +*> \ingroup doubleOTHERcomputational * -* DU2 (output) DOUBLE PRECISION array, dimension (N-2) -* On exit, DU2 is overwritten by the (n-2) elements of the -* second super-diagonal of U. +* ===================================================================== + SUBROUTINE DGTTRF( N, DL, D, DU, DU2, IPIV, INFO ) * -* IPIV (output) INTEGER array, dimension (N) -* The pivot indices; for 1 <= i <= n, row i of the matrix was -* interchanged with row IPIV(i). IPIV(i) will always be either -* i or i+1; IPIV(i) = i indicates a row interchange was not -* required. +* -- LAPACK computational 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 * -* INFO (output) INTEGER -* = 0: successful exit -* < 0: if INFO = -k, the k-th argument had an illegal value -* > 0: if INFO = k, U(k,k) is exactly zero. The factorization -* has been completed, but the factor U is exactly -* singular, and division by zero will occur if it is used -* to solve a system of equations. +* .. Scalar Arguments .. + INTEGER INFO, N +* .. +* .. Array Arguments .. + INTEGER IPIV( * ) + DOUBLE PRECISION D( * ), DL( * ), DU( * ), DU2( * ) +* .. * * ===================================================================== * |