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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine spbt01 | ( | character | UPLO, |
integer | N, | ||
integer | KD, | ||
real, dimension( lda, * ) | A, | ||
integer | LDA, | ||
real, dimension( ldafac, * ) | AFAC, | ||
integer | LDAFAC, | ||
real, dimension( * ) | RWORK, | ||
real | RESID | ||
) |
SPBT01
SPBT01 reconstructs a symmetric positive definite band matrix A from its L*L' or U'*U factorization and computes the residual norm( L*L' - A ) / ( N * norm(A) * EPS ) or norm( U'*U - A ) / ( N * norm(A) * EPS ), where EPS is the machine epsilon, L' is the conjugate transpose of L, and U' is the conjugate transpose of U.
[in] | UPLO | UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored: = 'U': Upper triangular = 'L': Lower triangular |
[in] | N | N is INTEGER The number of rows and columns of the matrix A. N >= 0. |
[in] | KD | KD is INTEGER The number of super-diagonals of the matrix A if UPLO = 'U', or the number of sub-diagonals if UPLO = 'L'. KD >= 0. |
[in] | A | A is REAL array, dimension (LDA,N) The original symmetric band matrix A. If UPLO = 'U', the upper triangular part of A is stored as a band matrix; if UPLO = 'L', the lower triangular part of A is stored. The columns of the appropriate triangle are stored in the columns of A and the diagonals of the triangle are stored in the rows of A. See SPBTRF for further details. |
[in] | LDA | LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,KD+1). |
[in] | AFAC | AFAC is REAL array, dimension (LDAFAC,N) The factored form of the matrix A. AFAC contains the factor L or U from the L*L' or U'*U factorization in band storage format, as computed by SPBTRF. |
[in] | LDAFAC | LDAFAC is INTEGER The leading dimension of the array AFAC. LDAFAC >= max(1,KD+1). |
[out] | RWORK | RWORK is REAL array, dimension (N) |
[out] | RESID | RESID is REAL If UPLO = 'L', norm(L*L' - A) / ( N * norm(A) * EPS ) If UPLO = 'U', norm(U'*U - A) / ( N * norm(A) * EPS ) |
Definition at line 121 of file spbt01.f.