TESTING/EIG/cunt01.f(3) | Library Functions Manual | TESTING/EIG/cunt01.f(3) |
NAME
TESTING/EIG/cunt01.f
SYNOPSIS
Functions/Subroutines
subroutine cunt01 (rowcol, m, n, u, ldu, work, lwork,
rwork, resid)
CUNT01
Function/Subroutine Documentation
subroutine cunt01 (character rowcol, integer m, integer n, complex, dimension( ldu, * ) u, integer ldu, complex, dimension( * ) work, integer lwork, real, dimension( * ) rwork, real resid)
CUNT01
Purpose:
CUNT01 checks that the matrix U is unitary by computing the ratio RESID = norm( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R', or RESID = norm( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'. Alternatively, if there isn't sufficient workspace to form I - U*U' or I - U'*U, the ratio is computed as RESID = abs( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R', or RESID = abs( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'. where EPS is the machine precision. ROWCOL is used only if m = n; if m > n, ROWCOL is assumed to be 'C', and if m < n, ROWCOL is assumed to be 'R'.
Parameters
ROWCOL
ROWCOL is CHARACTER Specifies whether the rows or columns of U should be checked for orthogonality. Used only if M = N. = 'R': Check for orthogonal rows of U = 'C': Check for orthogonal columns of U
M
M is INTEGER The number of rows of the matrix U.
N
N is INTEGER The number of columns of the matrix U.
U
U is COMPLEX array, dimension (LDU,N) The unitary matrix U. U is checked for orthogonal columns if m > n or if m = n and ROWCOL = 'C'. U is checked for orthogonal rows if m < n or if m = n and ROWCOL = 'R'.
LDU
LDU is INTEGER The leading dimension of the array U. LDU >= max(1,M).
WORK
WORK is COMPLEX array, dimension (LWORK)
LWORK
LWORK is INTEGER The length of the array WORK. For best performance, LWORK should be at least N*N if ROWCOL = 'C' or M*M if ROWCOL = 'R', but the test will be done even if LWORK is 0.
RWORK
RWORK is REAL array, dimension (min(M,N)) Used only if LWORK is large enough to use the Level 3 BLAS code.
RESID
RESID is REAL RESID = norm( I - U * U' ) / ( n * EPS ), if ROWCOL = 'R', or RESID = norm( I - U' * U ) / ( m * EPS ), if ROWCOL = 'C'.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 124 of file cunt01.f.
Author
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