sla_porcond (3) - Linux Manuals
REAL function sla_porcond (characterUPLO, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integerCMODE, real, dimension( * )C, integerINFO, real, dimension( * )WORK, integer, dimension( * )IWORK)
SLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.
SLA_PORCOND Estimates the Skeel condition number of op(A) * op2(C) where op2 is determined by CMODE as follows CMODE = 1 op2(C) = C CMODE = 0 op2(C) = I CMODE = -1 op2(C) = inv(C) The Skeel condition number cond(A) = norminf( |inv(A)||A| ) is computed by computing scaling factors R such that diag(R)*A*op2(C) is row equilibrated and computing the standard infinity-norm condition number.
UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.
A is REAL array, dimension (LDA,N) On entry, the N-by-N matrix A.
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
AF is REAL array, dimension (LDAF,N) The triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by SPOTRF.
LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).
CMODE is INTEGER Determines op2(C) in the formula op(A) * op2(C) as follows: CMODE = 1 op2(C) = C CMODE = 0 op2(C) = I CMODE = -1 op2(C) = inv(C)
C is REAL array, dimension (N) The vector C in the formula op(A) * op2(C).
INFO is INTEGER = 0: Successful exit. i > 0: The ith argument is invalid.
WORK is REAL array, dimension (3*N). Workspace.
IWORK is INTEGER array, dimension (N). Workspace.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
- September 2012
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