# dgtt02.f - Man Page

TESTING/LIN/dgtt02.f

## Synopsis

### Functions/Subroutines

subroutine dgtt02 (trans, n, nrhs, dl, d, du, x, ldx, b, ldb, resid)
DGTT02

## Function/Subroutine Documentation

### subroutine dgtt02 (character trans, integer n, integer nrhs, double precision, dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double precision, dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, * ) b, integer ldb, double precision resid)

DGTT02

Purpose:

DGTT02 computes the residual for the solution to a tridiagonal
system of equations:
RESID = norm(B - op(A)*X) / (norm(op(A)) * norm(X) * EPS),
where EPS is the machine epsilon.
The norm used is the 1-norm.
Parameters

TRANS

TRANS is CHARACTER
Specifies the form of the residual.
= 'N':  B - A    * X  (No transpose)
= 'T':  B - A**T * X  (Transpose)
= 'C':  B - A**H * X  (Conjugate transpose = Transpose)

N

N is INTEGER
The order of the matrix A.  N >= 0.

NRHS

NRHS is INTEGER
The number of right hand sides, i.e., the number of columns
of the matrices B and X.  NRHS >= 0.

DL

DL is DOUBLE PRECISION array, dimension (N-1)
The (n-1) sub-diagonal elements of A.

D

D is DOUBLE PRECISION array, dimension (N)
The diagonal elements of A.

DU

DU is DOUBLE PRECISION array, dimension (N-1)
The (n-1) super-diagonal elements of A.

X

X is DOUBLE PRECISION array, dimension (LDX,NRHS)
The computed solution vectors X.

LDX

LDX is INTEGER
The leading dimension of the array X.  LDX >= max(1,N).

B

B is DOUBLE PRECISION array, dimension (LDB,NRHS)
On entry, the right hand side vectors for the system of
linear equations.
On exit, B is overwritten with the difference B - op(A)*X.

LDB

LDB is INTEGER
The leading dimension of the array B.  LDB >= max(1,N).

RESID

RESID is DOUBLE PRECISION
norm(B - op(A)*X) / (norm(op(A)) * norm(X) * EPS)
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 123 of file dgtt02.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dgtt02(3) is an alias of dgtt02.f(3).

Tue Nov 28 2023 12:08:43 Version 3.12.0 LAPACK