--- rpl/lapack/lapack/dspsv.f 2011/07/22 07:38:11 1.8 +++ rpl/lapack/lapack/dspsv.f 2011/11/21 20:43:03 1.9 @@ -1,9 +1,171 @@ +*> \brief DSPSV computes the solution to system of linear equations A * X = B for OTHER matrices +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download DSPSV + dependencies +*> +*> [TGZ] +*> +*> [ZIP] +*> +*> [TXT] +*> \endhtmlonly +* +* Definition: +* =========== +* +* SUBROUTINE DSPSV( UPLO, N, NRHS, AP, IPIV, B, LDB, INFO ) +* +* .. Scalar Arguments .. +* CHARACTER UPLO +* INTEGER INFO, LDB, N, NRHS +* .. +* .. Array Arguments .. +* INTEGER IPIV( * ) +* DOUBLE PRECISION AP( * ), B( LDB, * ) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> DSPSV computes the solution to a real system of linear equations +*> A * X = B, +*> where A is an N-by-N symmetric matrix stored in packed format and X +*> and B are N-by-NRHS matrices. +*> +*> The diagonal pivoting method is used to factor A as +*> A = U * D * U**T, if UPLO = 'U', or +*> A = L * D * L**T, if UPLO = 'L', +*> where U (or L) is a product of permutation and unit upper (lower) +*> triangular matrices, D is symmetric and block diagonal with 1-by-1 +*> and 2-by-2 diagonal blocks. The factored form of A is then used to +*> solve the system of equations A * X = B. +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] UPLO +*> \verbatim +*> UPLO is CHARACTER*1 +*> = 'U': Upper triangle of A is stored; +*> = 'L': Lower triangle of A is stored. +*> \endverbatim +*> +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> The number of linear equations, i.e., the order of the +*> matrix A. N >= 0. +*> \endverbatim +*> +*> \param[in] NRHS +*> \verbatim +*> NRHS is INTEGER +*> The number of right hand sides, i.e., the number of columns +*> of the matrix B. NRHS >= 0. +*> \endverbatim +*> +*> \param[in,out] AP +*> \verbatim +*> AP is DOUBLE PRECISION array, dimension (N*(N+1)/2) +*> On entry, the upper or lower triangle of the symmetric matrix +*> A, packed columnwise in a linear array. The j-th column of A +*> is stored in the array AP as follows: +*> if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; +*> if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. +*> See below for further details. +*> +*> On exit, the block diagonal matrix D and the multipliers used +*> to obtain the factor U or L from the factorization +*> A = U*D*U**T or A = L*D*L**T as computed by DSPTRF, stored as +*> a packed triangular matrix in the same storage format as A. +*> \endverbatim +*> +*> \param[out] IPIV +*> \verbatim +*> IPIV is INTEGER array, dimension (N) +*> Details of the interchanges and the block structure of D, as +*> determined by DSPTRF. If IPIV(k) > 0, then rows and columns +*> k and IPIV(k) were interchanged, and D(k,k) is a 1-by-1 +*> diagonal block. If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, +*> then rows and columns k-1 and -IPIV(k) were interchanged and +*> D(k-1:k,k-1:k) is a 2-by-2 diagonal block. If UPLO = 'L' and +*> IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and +*> -IPIV(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2 +*> diagonal block. +*> \endverbatim +*> +*> \param[in,out] B +*> \verbatim +*> B is DOUBLE PRECISION array, dimension (LDB,NRHS) +*> On entry, the N-by-NRHS right hand side matrix B. +*> On exit, if INFO = 0, the N-by-NRHS solution matrix X. +*> \endverbatim +*> +*> \param[in] LDB +*> \verbatim +*> LDB is INTEGER +*> The leading dimension of the array B. LDB >= max(1,N). +*> \endverbatim +*> +*> \param[out] INFO +*> \verbatim +*> INFO is INTEGER +*> = 0: successful exit +*> < 0: if INFO = -i, the i-th argument had an illegal value +*> > 0: if INFO = i, D(i,i) is exactly zero. The factorization +*> has been completed, but the block diagonal matrix D is +*> exactly singular, so the solution could not be +*> computed. +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2011 +* +*> \ingroup doubleOTHERsolve +* +*> \par Further Details: +* ===================== +*> +*> \verbatim +*> +*> The packed storage scheme is illustrated by the following example +*> when N = 4, UPLO = 'U': +*> +*> Two-dimensional storage of the symmetric matrix A: +*> +*> a11 a12 a13 a14 +*> a22 a23 a24 +*> a33 a34 (aij = aji) +*> a44 +*> +*> Packed storage of the upper triangle of A: +*> +*> AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ] +*> \endverbatim +*> +* ===================================================================== SUBROUTINE DSPSV( UPLO, N, NRHS, AP, IPIV, B, LDB, INFO ) * -* -- LAPACK driver routine (version 3.3.1) -- +* -- LAPACK driver routine (version 3.4.0) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- -* -- April 2011 -- +* November 2011 * * .. Scalar Arguments .. CHARACTER UPLO @@ -14,93 +176,6 @@ DOUBLE PRECISION AP( * ), B( LDB, * ) * .. * -* Purpose -* ======= -* -* DSPSV computes the solution to a real system of linear equations -* A * X = B, -* where A is an N-by-N symmetric matrix stored in packed format and X -* and B are N-by-NRHS matrices. -* -* The diagonal pivoting method is used to factor A as -* A = U * D * U**T, if UPLO = 'U', or -* A = L * D * L**T, if UPLO = 'L', -* where U (or L) is a product of permutation and unit upper (lower) -* triangular matrices, D is symmetric and block diagonal with 1-by-1 -* and 2-by-2 diagonal blocks. The factored form of A is then used to -* solve the system of equations A * X = B. -* -* Arguments -* ========= -* -* UPLO (input) CHARACTER*1 -* = 'U': Upper triangle of A is stored; -* = 'L': Lower triangle of A is stored. -* -* N (input) INTEGER -* The number of linear equations, i.e., the order of the -* matrix A. N >= 0. -* -* NRHS (input) INTEGER -* The number of right hand sides, i.e., the number of columns -* of the matrix B. NRHS >= 0. -* -* AP (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2) -* On entry, the upper or lower triangle of the symmetric matrix -* A, packed columnwise in a linear array. The j-th column of A -* is stored in the array AP as follows: -* if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; -* if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. -* See below for further details. -* -* On exit, the block diagonal matrix D and the multipliers used -* to obtain the factor U or L from the factorization -* A = U*D*U**T or A = L*D*L**T as computed by DSPTRF, stored as -* a packed triangular matrix in the same storage format as A. -* -* IPIV (output) INTEGER array, dimension (N) -* Details of the interchanges and the block structure of D, as -* determined by DSPTRF. If IPIV(k) > 0, then rows and columns -* k and IPIV(k) were interchanged, and D(k,k) is a 1-by-1 -* diagonal block. If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, -* then rows and columns k-1 and -IPIV(k) were interchanged and -* D(k-1:k,k-1:k) is a 2-by-2 diagonal block. If UPLO = 'L' and -* IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and -* -IPIV(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2 -* diagonal block. -* -* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS) -* On entry, the N-by-NRHS right hand side matrix B. -* On exit, if INFO = 0, the N-by-NRHS solution matrix X. -* -* LDB (input) INTEGER -* The leading dimension of the array B. LDB >= max(1,N). -* -* INFO (output) INTEGER -* = 0: successful exit -* < 0: if INFO = -i, the i-th argument had an illegal value -* > 0: if INFO = i, D(i,i) is exactly zero. The factorization -* has been completed, but the block diagonal matrix D is -* exactly singular, so the solution could not be -* computed. -* -* Further Details -* =============== -* -* The packed storage scheme is illustrated by the following example -* when N = 4, UPLO = 'U': -* -* Two-dimensional storage of the symmetric matrix A: -* -* a11 a12 a13 a14 -* a22 a23 a24 -* a33 a34 (aij = aji) -* a44 -* -* Packed storage of the upper triangle of A: -* -* AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ] -* * ===================================================================== * * .. External Functions ..