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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 stpt06 | ( | real | RCOND, |
| real | RCONDC, | ||
| character | UPLO, | ||
| character | DIAG, | ||
| integer | N, | ||
| real, dimension( * ) | AP, | ||
| real, dimension( * ) | WORK, | ||
| real | RAT | ||
| ) |
STPT06
STPT06 computes a test ratio comparing RCOND (the reciprocal condition number of a triangular matrix A) and RCONDC, the estimate computed by STPCON. Information about the triangular matrix A 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
STPCON. |
| [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 REAL 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] | WORK | WORK 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