NR1RR
Computes the 1-norm of a real matrix.
Required Arguments
A — Real NRA by NCA matrix whose 1-norm is to be computed. (Input)
ANORM — Real scalar containing the 1-norm of A. (Output)
Optional Arguments
NRA — Number of rows of A. (Input)
Default: NRA = SIZE (A,1).
NCA — Number of columns of A. (Input)
Default: NCA = SIZE (A,2).
LDA — Leading dimension of A exactly as specified in the dimension statement of the calling program. (Input)
Default: LDA = SIZE (A,1).
FORTRAN 90 Interface
Generic: CALL NR1RR (A, ANORM [, …])
Specific: The specific interface names are S_NR1RR and D_NR1RR.
FORTRAN 77 Interface
Single: CALL NR1RR (NRA, NCA, A, LDA, ANORM)
Double: The double precision name is DNR1RR.
Description
The routine NR1RR computes the 1-norm of a real rectangular matrix A. If m = NRA and n = NCA, then the 1-norm of A is
This is the maximum of the sums of the absolute values of the column elements.
Example
Compute the 1-norm of a 3 × 4 real rectangular matrix.
USE NR1RR_INT
USE UMACH_INT
IMPLICIT NONE
! Declare variables
INTEGER NCA, NRA
PARAMETER (NCA=4, NRA=3)
!
INTEGER NOUT
REAL A(NRA,NCA), ANORM
!
! Set values for A
! A = ( 1.0 0.0 2.0 0.0 )
! ( 3.0 4.0 -1.0 0.0 )
! ( 2.0 1.0 2.0 1.0 )
!
DATA A/1.0, 3.0, 2.0, 0.0, 4.0, 1.0, 2.0, -1.0, 2.0, 0.0, 0.0, &
1.0/
! Compute the L1 norm of A
CALL NR1RR (A, ANORM)
! Print results
CALL UMACH (2, NOUT)
WRITE (NOUT,*) ' The 1-norm of A is ', ANORM
END
Output
The 1-norm of A is 6.00000
