LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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spttrf.f File Reference

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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

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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:
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in,out]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.
[in,out]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.
[out]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:
November 2011

Definition at line 92 of file spttrf.f.

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