
NAMEztbcon.f SYNOPSISFunctions/Subroutinessubroutine ztbcon (NORM, UPLO, DIAG, N, KD, AB, LDAB, RCOND, WORK, RWORK, INFO) Function/Subroutine Documentationsubroutine ztbcon (characterNORM, characterUPLO, characterDIAG, integerN, integerKD, complex*16, dimension( ldab, * )AB, integerLDAB, double precisionRCOND, complex*16, dimension( * )WORK, double precision, dimension( * )RWORK, integerINFO)ZTBCON Purpose:ZTBCON estimates the reciprocal of the condition number of a triangular band matrix A, in either the 1norm or the infinitynorm. The norm of A is computed and an estimate is obtained for norm(inv(A)), then the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A)) ). NORM
Author:
NORM is CHARACTER*1 Specifies whether the 1norm condition number or the infinitynorm condition number is required: = '1' or 'O': 1norm; = 'I': Infinitynorm.UPLO UPLO is CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular.DIAG DIAG is CHARACTER*1 = 'N': A is nonunit triangular; = 'U': A is unit triangular.N N is INTEGER The order of the matrix A. N >= 0.KD KD is INTEGER The number of superdiagonals or subdiagonals of the triangular band matrix A. KD >= 0.AB AB is COMPLEX*16 array, dimension (LDAB,N) The upper or lower triangular band matrix A, stored in the first kd+1 rows of the array. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = 'U', AB(kd+1+ij,j) = A(i,j) for max(1,jkd)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+kd). If DIAG = 'U', the diagonal elements of A are not referenced and are assumed to be 1.LDAB LDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1.RCOND RCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).WORK WORK is COMPLEX*16 array, dimension (2*N)RWORK RWORK is DOUBLE PRECISION array, dimension (N)INFO INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Definition at line 143 of file ztbcon.f.
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