Provided by: liblapack-doc_3.12.0-3build1.1_all bug

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.

   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.

   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.

   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.

Author

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