Quick Navigator

 Search Site Miscellaneous Server Agreement Year 2038 Credits
 ztprfs.f(3) LAPACK ztprfs.f(3)

ztprfs.f -

# SYNOPSIS

## Functions/Subroutines

subroutine ztprfs (UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, X, LDX, FERR, BERR, WORK, RWORK, INFO)

ZTPRFS

# Function/Subroutine Documentation

## subroutine ztprfs (characterUPLO, characterTRANS, characterDIAG, integerN, integerNRHS, complex*16, dimension( * )AP, complex*16, dimension( ldb, * )B, integerLDB, complex*16, dimension( ldx, * )X, integerLDX, double precision, dimension( * )FERR, double precision, dimension( * )BERR, complex*16, dimension( * )WORK, double precision, dimension( * )RWORK, integerINFO)

ZTPRFS
Purpose:
``` ZTPRFS provides error bounds and backward error estimates for the
solution to a system of linear equations with a triangular packed
coefficient matrix.

The solution matrix X must be computed by ZTPTRS or some other
means before entering this routine.  ZTPRFS does not do iterative
refinement because doing so cannot improve the backward error.
```
Parameters:
UPLO
```          UPLO is CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.
```
TRANS
```          TRANS is CHARACTER*1
Specifies the form of the system of equations:
= 'N':  A * X = B     (No transpose)
= 'T':  A**T * X = B  (Transpose)
= 'C':  A**H * X = B  (Conjugate transpose)
```
DIAG
```          DIAG is CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.
```
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.
```
AP
```          AP is COMPLEX*16 array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed columnwise in
a linear array.  The j-th column of A is stored in the array
AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
If DIAG = 'U', the diagonal elements of A are not referenced
and are assumed to be 1.
```
B
```          B is COMPLEX*16 array, dimension (LDB,NRHS)
The right hand side matrix B.
```
LDB
```          LDB is INTEGER
The leading dimension of the array B.  LDB >= max(1,N).
```
X
```          X is COMPLEX*16 array, dimension (LDX,NRHS)
The solution matrix X.
```
LDX
```          LDX is INTEGER
The leading dimension of the array X.  LDX >= max(1,N).
```
FERR
```          FERR is DOUBLE PRECISION array, dimension (NRHS)
The estimated forward error bound for each solution vector
X(j) (the j-th column of the solution matrix X).
If XTRUE is the true solution corresponding to X(j), FERR(j)
is an estimated upper bound for the magnitude of the largest
element in (X(j) - XTRUE) divided by the magnitude of the
largest element in X(j).  The estimate is as reliable as
the estimate for RCOND, and is almost always a slight
overestimate of the true error.
```
BERR
```          BERR is DOUBLE PRECISION array, dimension (NRHS)
The componentwise relative backward error of each solution
vector X(j) (i.e., the smallest relative change in
any element of A or B that makes X(j) an exact solution).
```
WORK
```          WORK is COMPLEX*16 array, dimension (2*N)
```
RWORK
```          RWORK is DOUBLE PRECISION array, dimension (N)
```
INFO
```          INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-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 174 of file ztprfs.f.

# Author

Generated automatically by Doxygen for LAPACK from the source code.
 Sat Nov 16 2013 Version 3.4.2

Search for    or go to Top of page |  Section 3 |  Main Index

Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.