LAPACK  3.5.0
LAPACK: Linear Algebra PACKage
 All Classes Files Functions Variables Typedefs Macros
sgtt01.f File Reference

Go to the source code of this file.

Functions/Subroutines

subroutine sgtt01 (N, DL, D, DU, DLF, DF, DUF, DU2, IPIV, WORK, LDWORK, RWORK, RESID)
 SGTT01 More...
 

Function/Subroutine Documentation

subroutine sgtt01 ( integer  N,
real, dimension( * )  DL,
real, dimension( * )  D,
real, dimension( * )  DU,
real, dimension( * )  DLF,
real, dimension( * )  DF,
real, dimension( * )  DUF,
real, dimension( * )  DU2,
integer, dimension( * )  IPIV,
real, dimension( ldwork, * )  WORK,
integer  LDWORK,
real, dimension( * )  RWORK,
real  RESID 
)

SGTT01

Purpose:
 SGTT01 reconstructs a tridiagonal matrix A from its LU factorization
 and computes the residual
    norm(L*U - A) / ( norm(A) * EPS ),
 where EPS is the machine epsilon.
Parameters
[in]N
          N is INTEGTER
          The order of the matrix A.  N >= 0.
[in]DL
          DL is REAL array, dimension (N-1)
          The (n-1) sub-diagonal elements of A.
[in]D
          D is REAL array, dimension (N)
          The diagonal elements of A.
[in]DU
          DU is REAL array, dimension (N-1)
          The (n-1) super-diagonal elements of A.
[in]DLF
          DLF is REAL array, dimension (N-1)
          The (n-1) multipliers that define the matrix L from the
          LU factorization of A.
[in]DF
          DF is REAL array, dimension (N)
          The n diagonal elements of the upper triangular matrix U from
          the LU factorization of A.
[in]DUF
          DUF is REAL array, dimension (N-1)
          The (n-1) elements of the first super-diagonal of U.
[in]DU2
          DU2 is REAL array, dimension (N-2)
          The (n-2) elements of the second super-diagonal of U.
[in]IPIV
          IPIV is INTEGER array, dimension (N)
          The pivot indices; for 1 <= i <= n, row i of the matrix was
          interchanged with row IPIV(i).  IPIV(i) will always be either
          i or i+1; IPIV(i) = i indicates a row interchange was not
          required.
[out]WORK
          WORK is REAL array, dimension (LDWORK,N)
[in]LDWORK
          LDWORK is INTEGER
          The leading dimension of the array WORK.  LDWORK >= max(1,N).
[out]RWORK
          RWORK is REAL array, dimension (N)
[out]RESID
          RESID is REAL
          The scaled residual:  norm(L*U - A) / (norm(A) * EPS)
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
November 2011

Definition at line 134 of file sgtt01.f.

Here is the call graph for this function:

Here is the caller graph for this function: