# ctpt01.f - Man Page

TESTING/LIN/ctpt01.f

## Synopsis

### Functions/Subroutines

subroutine ctpt01 (uplo, diag, n, ap, ainvp, rcond, rwork, resid)
CTPT01

## Function/Subroutine Documentation

### subroutine ctpt01 (character uplo, character diag, integer n, complex, dimension( * ) ap, complex, dimension( * ) ainvp, real rcond, real, dimension( * ) rwork, real resid)

CTPT01

Purpose:

``` CTPT01 computes the residual for a triangular matrix A times its
inverse when A is stored in packed format:
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.```

AP

```          AP is COMPLEX array, dimension (N*(N+1)/2)
The original 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((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
if UPLO = 'L',
AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.```

AINVP

```          AINVP is COMPLEX array, dimension (N*(N+1)/2)
On entry, the (triangular) inverse of the matrix A, packed
columnwise in a linear array as in AP.
On exit, the contents of AINVP are destroyed.```

RCOND

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

RWORK

`          RWORK 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 108 of file ctpt01.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page ctpt01(3) is an alias of ctpt01.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK