LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
spttrs.f File Reference

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Functions/Subroutines

subroutine SPTTRS (N, NRHS, D, E, B, LDB, INFO)
 SPTTRS

Function/Subroutine Documentation

subroutine SPTTRS ( INTEGER  N,
INTEGER  NRHS,
REAL, dimension( * )  D,
REAL, dimension( * )  E,
REAL, dimension( ldb, * )  B,
INTEGER  LDB,
INTEGER  INFO 
)

SPTTRS

Download SPTTRS + dependencies [TGZ] [ZIP] [TXT]
Purpose:

 SPTTRS solves a tridiagonal system of the form
    A * X = B
 using the L*D*L**T factorization of A computed by SPTTRF.  D is a
 diagonal matrix specified in the vector D, L is a unit bidiagonal
 matrix whose subdiagonal is specified in the vector E, and X and B
 are N by NRHS matrices.
 
Parameters:
[in]N
          N is INTEGER
          The order of the tridiagonal matrix A.  N >= 0.
 
[in]NRHS
          NRHS is INTEGER
          The number of right hand sides, i.e., the number of columns
          of the matrix B.  NRHS >= 0.
 
[in]D
          D is REAL array, dimension (N)
          The n diagonal elements of the diagonal matrix D from the
          L*D*L**T factorization of A.
 
[in]E
          E is REAL array, dimension (N-1)
          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
          factorization A = U**T*D*U.
 
[in,out]B
          B is REAL array, dimension (LDB,NRHS)
          On entry, the right hand side vectors B for the system of
          linear equations.
          On exit, the solution vectors, X.
 
[in]LDB
          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).
 
[out]INFO
          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -k, the k-th argument had an illegal value
 
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011

Definition at line 110 of file spttrs.f.

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