# dtrt06.f - Man Page

TESTING/LIN/dtrt06.f

## Synopsis

### Functions/Subroutines

subroutine dtrt06 (rcond, rcondc, uplo, diag, n, a, lda, work, rat)
DTRT06

## Function/Subroutine Documentation

### subroutine dtrt06 (double precision rcond, double precision rcondc, character uplo, character diag, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) work, double precision rat)

DTRT06

Purpose:

``` DTRT06 computes a test ratio comparing RCOND (the reciprocal
condition number of a triangular matrix A) and RCONDC, the estimate
computed by DTRCON.  Information about the triangular matrix A is
used if one estimate is zero and the other is non-zero to decide if
underflow in the estimate is justified.```
Parameters

RCOND

```          RCOND is DOUBLE PRECISION
The estimate of the reciprocal condition number obtained by
forming the explicit inverse of the matrix A and computing
RCOND = 1/( norm(A) * norm(inv(A)) ).```

RCONDC

```          RCONDC is DOUBLE PRECISION
The estimate of the reciprocal condition number computed by
DTRCON.```

UPLO

```          UPLO is CHARACTER
Specifies whether the matrix A is upper or lower triangular.
= 'U':  Upper triangular
= 'L':  Lower triangular```

DIAG

```          DIAG is CHARACTER
Specifies whether or not the matrix A is unit triangular.
= 'N':  Non-unit triangular
= 'U':  Unit triangular```

N

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

A

```          A is DOUBLE PRECISION array, dimension (LDA,N)
The triangular matrix A.  If UPLO = 'U', the leading n by n
upper triangular part of the array A contains the upper
triangular matrix, and the strictly lower triangular part of
A is not referenced.  If UPLO = 'L', the leading n by n lower
triangular part of the array A contains the lower triangular
matrix, and the strictly upper triangular part of A is not
referenced.  If DIAG = 'U', the diagonal elements of A are
also not referenced and are assumed to be 1.```

LDA

```          LDA is INTEGER
The leading dimension of the array A.  LDA >= max(1,N).```

WORK

`          WORK is DOUBLE PRECISION array, dimension (N)`

RAT

```          RAT is DOUBLE PRECISION
The test ratio.  If both RCOND and RCONDC are nonzero,
RAT = MAX( RCOND, RCONDC )/MIN( RCOND, RCONDC ) - 1.
If RAT = 0, the two estimates are exactly the same.```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 119 of file dtrt06.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dtrt06(3) is an alias of dtrt06.f(3).

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