LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  spttrf (N, D, E, INFO) 
SPTTRF 
subroutine spttrf  (  integer  N, 
real, dimension( * )  D,  
real, dimension( * )  E,  
integer  INFO  
) 
SPTTRF
Download SPTTRF + dependencies [TGZ] [ZIP] [TXT]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.
[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 (N1) On entry, the (n1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n1) 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 kth 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. 
Definition at line 92 of file spttrf.f.