# strt01.f - Man Page

TESTING/LIN/strt01.f

## Synopsis

### Functions/Subroutines

subroutine strt01 (uplo, diag, n, a, lda, ainv, ldainv, rcond, work, resid)
STRT01

## Function/Subroutine Documentation

### subroutine strt01 (character uplo, character diag, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( ldainv, * ) ainv, integer ldainv, real rcond, real, dimension( * ) work, real resid)

STRT01

Purpose:

``` STRT01 computes the residual for a triangular matrix A times its
inverse:
RESID = norm( A*AINV - I ) / ( N * norm(A) * norm(AINV) * EPS ),
where EPS is the machine epsilon.```
Parameters

UPLO

```          UPLO is CHARACTER*1
Specifies whether the matrix A is upper or lower triangular.
= 'U':  Upper triangular
= 'L':  Lower triangular```

DIAG

```          DIAG is CHARACTER*1
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 REAL 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).```

AINV

```          AINV is REAL array, dimension (LDAINV,N)
On entry, the (triangular) inverse of the matrix A, in the
same storage format as A.
On exit, the contents of AINV are destroyed.```

LDAINV

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

RCOND

```          RCOND is REAL
The reciprocal condition number of A, computed as
1/(norm(A) * norm(AINV)).```

WORK

`          WORK is REAL array, dimension (N)`

RESID

```          RESID is REAL
norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS )```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 122 of file strt01.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page strt01(3) is an alias of strt01.f(3).

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