f07ce_ad_f : NAG AD Library Routine Document, Mark 26

Fortran Interface

Subroutine f07ce_a1w_f (

ad_handle, trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, ifail)

Integer, Intent (In)	::	n, nrhs, ipiv(*), ldb
Integer, Intent (Out)	::	info
Type (nagad_a1w_w_rtype), Intent (In)	::	dl(), d(), du(), du2()
Type (nagad_a1w_w_rtype), Intent (Inout)	::	b(ldb,*)
Character (1), Intent (In)	::	trans
Type (c_ptr), Intent (In)	::	ad_handle

C++ Header Interface

#include <nagad.h>

void f07ce_a1w_f_ (

void *&ad_handle, const char *trans, const Integer &n, const Integer &nrhs, nagad_a1w_w_rtype dl[], nagad_a1w_w_rtype d[], nagad_a1w_w_rtype du[], nagad_a1w_w_rtype du2[], Integer ipiv[], nagad_a1w_w_rtype b[], const Integer &ldb, Integer &ifail, const Charlen length_trans)

Description

f07cef (dgttrs) computes the solution to a real system of linear equations

A X = B

A^{T} X = B

, where

A

is an

n

n

tridiagonal matrix and

X

and

B

are

n

r

matrices, using the

L U

factorization returned by f07cdf (dgttrf). For further information see Section 3 in the documentation for f07cef (dgttrs).

References

Arguments

f07ce_a1w_f provides access to all the arguments available in the primal routine. There are also additional arguments specific to AD. A tooltip popup for each argument can be found by hovering over the argument name in Section 2 and a summary of the arguments are provided below:

ad_handle – a handle to the AD configuration data object, as created by x10aa_a1w_f.
trans – specifies the equations to be solved as follows.
n – $n$ , the order of the matrix $A$ .
nrhs – $r$ , the number of right-hand sides, i.e., the number of columns of the matrix $B$ .
dl – must contain the $(n - 1)$ multipliers that define the matrix $L$ of the $L U$ factorization of $A$ .
d – must contain the $n$ diagonal elements of the upper triangular matrix $U$ from the $L U$ factorization of $A$ .
du – must contain the $(n - 1)$ elements of the first superdiagonal of $U$ .
du2 – must contain the $(n - 2)$ elements of the second superdiagonal of $U$ .
ipiv – must contain the $n$ pivot indices that define the permutation matrix $P$ .
b – on entry: the $n$ by $r$ matrix of right-hand sides $B$ . on exit: the $n$ by $r$ solution matrix $X$ .
ldb – the first dimension of the array b.
ifail – on exit: $ifail = 0$ unless the routine detects an error (see Section 6).

Error Indicators and Warnings

f07ce_a1w_f uses the standard NAG ifail mechanism. Any errors indicated via info values returned by f07cef may be indicated with the same value returned by ifail. In addition, this routine may return:

$ifail = - 89$: An unexpected AD error has been triggered by this routine. Please contact NAG.
See Section 5.2 in the NAG AD Library Introduction for further information.

$ifail = - 899$: Dynamic memory allocation failed for AD.
See Section 5.1 in the NAG AD Library Introduction for further information.

Language	Source File	Data	Results
Fortan	f07ce_a1w_fe.f90	f07ce_a1w_fe.d	f07ce_a1w_fe.r
C++	f07ce_a1w_hcppe.cpp	f07ce_a1w_hcppe.d	f07ce_a1w_hcppe.r

NAG AD Library Routine Document

f07ce_a1w_f (dgttrs_a1w)

▸▿ Contents

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

6

Error Indicators and Warnings

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example

NAG AD Library Routine Document

f07ce_a1w_f (dgttrs_a1w)

▸▿ Contents

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example