pttrf(3) Library Functions Manual pttrf(3) NAME pttrf - pttrf: triangular factor SYNOPSIS Functions subroutine cpttrf (n, d, e, info) CPTTRF subroutine dpttrf (n, d, e, info) DPTTRF subroutine spttrf (n, d, e, info) SPTTRF subroutine zpttrf (n, d, e, info) ZPTTRF Detailed Description Function Documentation subroutine cpttrf (integer n, real, dimension( * ) d, complex, dimension( * ) e, integer info) CPTTRF Purpose: !> !> CPTTRF computes the L*D*L**H factorization of a complex Hermitian !> positive definite tridiagonal matrix A. The factorization may also !> be regarded as having the form A = U**H *D*U. !> Parameters N !> N is INTEGER !> The order of the matrix A. N >= 0. !> D !> D is REAL array, dimension (N) !> On entry, the n diagonal elements of the tridiagonal matrix !> A. On exit, the n diagonal elements of the diagonal matrix !> D from the L*D*L**H factorization of A. !> E !> E is COMPLEX array, dimension (N-1) !> On entry, the (n-1) subdiagonal elements of the tridiagonal !> matrix A. On exit, the (n-1) subdiagonal elements of the !> unit bidiagonal factor L from the L*D*L**H factorization of A. !> E can also be regarded as the superdiagonal of the unit !> bidiagonal factor U from the U**H *D*U factorization of A. !> INFO !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !> > 0: if INFO = k, the leading principal minor of order k !> is not positive; if k < N, the factorization could not !> be completed, while if k = N, the factorization was !> completed, but D(N) <= 0. !> Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Definition at line 91 of file cpttrf.f. subroutine dpttrf (integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, integer info) DPTTRF Purpose: !> !> DPTTRF computes the L*D*L**T factorization of a real symmetric !> positive definite tridiagonal matrix A. The factorization may also !> be regarded as having the form A = U**T*D*U. !> Parameters N !> N is INTEGER !> The order of the matrix A. N >= 0. !> D !> D is DOUBLE PRECISION array, dimension (N) !> On entry, the n diagonal elements of the tridiagonal matrix !> A. On exit, the n diagonal elements of the diagonal matrix !> D from the L*D*L**T factorization of A. !> E !> E is DOUBLE PRECISION array, dimension (N-1) !> On entry, the (n-1) subdiagonal elements of the tridiagonal !> matrix A. On exit, the (n-1) subdiagonal elements of the !> unit bidiagonal factor L from the L*D*L**T factorization of A. !> E can also be regarded as the superdiagonal of the unit !> bidiagonal factor U from the U**T*D*U factorization of A. !> INFO !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !> > 0: if INFO = k, the leading principal minor of order k !> is not positive; if k < N, the factorization could not !> be completed, while if k = N, the factorization was !> completed, but D(N) <= 0. !> Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Definition at line 90 of file dpttrf.f. subroutine spttrf (integer n, real, dimension( * ) d, real, dimension( * ) e, integer info) SPTTRF Purpose: !> !> SPTTRF computes the L*D*L**T factorization of a real symmetric !> positive definite tridiagonal matrix A. The factorization may also !> be regarded as having the form A = U**T*D*U. !> Parameters N !> N is INTEGER !> The order of the matrix A. N >= 0. !> D !> D is REAL array, dimension (N) !> On entry, the n diagonal elements of the tridiagonal matrix !> A. On exit, the n diagonal elements of the diagonal matrix !> D from the L*D*L**T factorization of A. !> E !> E is REAL array, dimension (N-1) !> On entry, the (n-1) subdiagonal elements of the tridiagonal !> matrix A. On exit, the (n-1) subdiagonal elements of the !> unit bidiagonal factor L from the L*D*L**T factorization of A. !> E can also be regarded as the superdiagonal of the unit !> bidiagonal factor U from the U**T*D*U factorization of A. !> INFO !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !> > 0: if INFO = k, the leading principal minor of order k !> is not positive; if k < N, the factorization could not !> be completed, while if k = N, the factorization was !> completed, but D(N) <= 0. !> Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Definition at line 90 of file spttrf.f. subroutine zpttrf (integer n, double precision, dimension( * ) d, complex*16, dimension( * ) e, integer info) ZPTTRF Purpose: !> !> ZPTTRF computes the L*D*L**H factorization of a complex Hermitian !> positive definite tridiagonal matrix A. The factorization may also !> be regarded as having the form A = U**H *D*U. !> Parameters N !> N is INTEGER !> The order of the matrix A. N >= 0. !> D !> D is DOUBLE PRECISION array, dimension (N) !> On entry, the n diagonal elements of the tridiagonal matrix !> A. On exit, the n diagonal elements of the diagonal matrix !> D from the L*D*L**H factorization of A. !> E !> E is COMPLEX*16 array, dimension (N-1) !> On entry, the (n-1) subdiagonal elements of the tridiagonal !> matrix A. On exit, the (n-1) subdiagonal elements of the !> unit bidiagonal factor L from the L*D*L**H factorization of A. !> E can also be regarded as the superdiagonal of the unit !> bidiagonal factor U from the U**H *D*U factorization of A. !> INFO !> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !> > 0: if INFO = k, the leading principal minor of order k !> is not positive; if k < N, the factorization could not !> be completed, while if k = N, the factorization was !> completed, but D(N) <= 0. !> Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Definition at line 91 of file zpttrf.f. Author Generated automatically by Doxygen for LAPACK from the source code. LAPACK Version 3.12.0 pttrf(3)