# 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

Univ. of Colorado Denver

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