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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| subroutine ctpt06 | ( | real | RCOND, |
| real | RCONDC, | ||
| character | UPLO, | ||
| character | DIAG, | ||
| integer | N, | ||
| complex, dimension( * ) | AP, | ||
| real, dimension( * ) | RWORK, | ||
| real | RAT | ||
| ) |
CTPT06
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.
| [in] | 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)) ). |
| [in] | RCONDC | RCONDC is REAL
The estimate of the reciprocal condition number computed by
CTPCON. |
| [in] | UPLO | UPLO is CHARACTER
Specifies whether the matrix A is upper or lower triangular.
= 'U': Upper triangular
= 'L': Lower triangular |
| [in] | DIAG | DIAG is CHARACTER
Specifies whether or not the matrix A is unit triangular.
= 'N': Non-unit triangular
= 'U': Unit triangular |
| [in] | N | N is INTEGER
The order of the matrix A. N >= 0. |
| [in] | 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. |
| [out] | RWORK | RWORK is REAL array, dimension (N) |
| [out] | 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. |
1.9.4