# 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

Univ. of Colorado Denver

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