TESTING/LIN/ctpt06.f(3) | Library Functions Manual | TESTING/LIN/ctpt06.f(3) |
NAME
TESTING/LIN/ctpt06.f
SYNOPSIS
Functions/Subroutines
subroutine ctpt06 (rcond, rcondc, uplo, diag, n, ap, rwork,
rat)
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.
Author
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