ctpt063
Part of ctpt06.f(3).
Usage
Functions/Subroutines
CTPT06
Function/Subroutine Documentation
subroutine ctpt06 (real rcond, real rcondc, character uplo, character diag, integer n, complex, dimension( * ) ap, real, dimension( * ) rwork, real rat)
CTPT06
Purpose:
!> !> CTPT06 computes a test ratio comparing RCOND (the reciprocal !> condition number of the triangular matrix A) and RCONDC, the estimate !> computed by CTPCON. Information about the triangular matrix 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 REAL !> 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 REAL !> The estimate of the reciprocal condition number computed by !> CTPCON. !>
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. !>
AP
!> AP is COMPLEX array, dimension (N*(N+1)/2) !> The 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. !>
RWORK
!> RWORK is REAL array, dimension (N) !>
RAT
!> RAT is REAL !> 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
Univ. of Colorado Denver
NAG Ltd.
Definition at line 111 of file ctpt06.f.