table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlansf.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlansf.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlansf.f
SYNOPSIS¶
Functions/Subroutines¶
double precision function DLANSF (norm, transr, uplo, n, a,
work)
DLANSF returns the value of the 1-norm, or the Frobenius norm, or the
infinity norm, or the element of largest absolute value of a symmetric
matrix in RFP format.
Function/Subroutine Documentation¶
double precision function DLANSF (character norm, character transr, character uplo, integer n, double precision, dimension( 0: * ) a, double precision, dimension( 0: * ) work)¶
DLANSF returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric matrix in RFP format.
Purpose:
!> !> DLANSF returns the value of the one norm, or the Frobenius norm, or !> the infinity norm, or the element of largest absolute value of a !> real symmetric matrix A in RFP format. !>
Returns
DLANSF
!> !> DLANSF = ( max(abs(A(i,j))), NORM = 'M' or 'm' !> ( !> ( norm1(A), NORM = '1', 'O' or 'o' !> ( !> ( normI(A), NORM = 'I' or 'i' !> ( !> ( normF(A), NORM = 'F', 'f', 'E' or 'e' !> !> where norm1 denotes the one norm of a matrix (maximum column sum), !> normI denotes the infinity norm of a matrix (maximum row sum) and !> normF denotes the Frobenius norm of a matrix (square root of sum of !> squares). Note that max(abs(A(i,j))) is not a matrix norm. !>
Parameters
NORM
!> NORM is CHARACTER*1 !> Specifies the value to be returned in DLANSF as described !> above. !>
TRANSR
!> TRANSR is CHARACTER*1 !> Specifies whether the RFP format of A is normal or !> transposed format. !> = 'N': RFP format is Normal; !> = 'T': RFP format is Transpose. !>
UPLO
!> UPLO is CHARACTER*1 !> On entry, UPLO specifies whether the RFP matrix A came from !> an upper or lower triangular matrix as follows: !> = 'U': RFP A came from an upper triangular matrix; !> = 'L': RFP A came from a lower triangular matrix. !>
N
!> N is INTEGER !> The order of the matrix A. N >= 0. When N = 0, DLANSF is !> set to zero. !>
A
!> A is DOUBLE PRECISION array, dimension ( N*(N+1)/2 ); !> On entry, the upper (if UPLO = 'U') or lower (if UPLO = 'L') !> part of the symmetric matrix A stored in RFP format. See the !> below for more details. !> Unchanged on exit. !>
WORK
!> WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)), !> where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, !> WORK is not referenced. !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> We first consider Rectangular Full Packed (RFP) Format when N is !> even. We give an example where N = 6. !> !> AP is Upper AP is Lower !> !> 00 01 02 03 04 05 00 !> 11 12 13 14 15 10 11 !> 22 23 24 25 20 21 22 !> 33 34 35 30 31 32 33 !> 44 45 40 41 42 43 44 !> 55 50 51 52 53 54 55 !> !> !> Let TRANSR = 'N'. RFP holds AP as follows: !> For UPLO = 'U' the upper trapezoid A(0:5,0:2) consists of the last !> three columns of AP upper. The lower triangle A(4:6,0:2) consists of !> the transpose of the first three columns of AP upper. !> For UPLO = 'L' the lower trapezoid A(1:6,0:2) consists of the first !> three columns of AP lower. The upper triangle A(0:2,0:2) consists of !> the transpose of the last three columns of AP lower. !> This covers the case N even and TRANSR = 'N'. !> !> RFP A RFP A !> !> 03 04 05 33 43 53 !> 13 14 15 00 44 54 !> 23 24 25 10 11 55 !> 33 34 35 20 21 22 !> 00 44 45 30 31 32 !> 01 11 55 40 41 42 !> 02 12 22 50 51 52 !> !> Now let TRANSR = 'T'. RFP A in both UPLO cases is just the !> transpose of RFP A above. One therefore gets: !> !> !> RFP A RFP A !> !> 03 13 23 33 00 01 02 33 00 10 20 30 40 50 !> 04 14 24 34 44 11 12 43 44 11 21 31 41 51 !> 05 15 25 35 45 55 22 53 54 55 22 32 42 52 !> !> !> We then consider Rectangular Full Packed (RFP) Format when N is !> odd. We give an example where N = 5. !> !> AP is Upper AP is Lower !> !> 00 01 02 03 04 00 !> 11 12 13 14 10 11 !> 22 23 24 20 21 22 !> 33 34 30 31 32 33 !> 44 40 41 42 43 44 !> !> !> Let TRANSR = 'N'. RFP holds AP as follows: !> For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last !> three columns of AP upper. The lower triangle A(3:4,0:1) consists of !> the transpose of the first two columns of AP upper. !> For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first !> three columns of AP lower. The upper triangle A(0:1,1:2) consists of !> the transpose of the last two columns of AP lower. !> This covers the case N odd and TRANSR = 'N'. !> !> RFP A RFP A !> !> 02 03 04 00 33 43 !> 12 13 14 10 11 44 !> 22 23 24 20 21 22 !> 00 33 34 30 31 32 !> 01 11 44 40 41 42 !> !> Now let TRANSR = 'T'. RFP A in both UPLO cases is just the !> transpose of RFP A above. One therefore gets: !> !> RFP A RFP A !> !> 02 12 22 00 01 00 10 20 30 40 50 !> 03 13 23 33 11 33 11 21 31 41 51 !> 04 14 24 34 44 43 44 22 32 42 52 !>
Definition at line 208 of file dlansf.f.
Author¶
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