spttrf.f man page

spttrf.f

Synopsis

Functions/Subroutines

subroutine spttrf (N, D, E, INFO)
SPTTRF

Function/Subroutine Documentation

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 minor of order k is not
               positive definite; 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.

Date:

December 2016

Definition at line 93 of file spttrf.f.

Author

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Referenced By

The man page spttrf(3) is an alias of spttrf.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK