NR1CB

Computes the 1-norm of a complex band matrix in band storage mode.

Required Arguments

A — Complex (NUCA + NLCA + 1) by N array containing the N by N band matrix in band storage mode. (Input)

NLCA — Number of lower codiagonals of A. (Input)

NUCA — Number of upper codiagonals of A. (Input)

ANORM — Real scalar containing the 1-norm of A. (Output)

N — Order of the matrix. (Input)
Default: N = 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).

Generic: CALL NR1CB (A, NLCA, NUCA, ANORM [, …])

Specific: The specific interface names are S_NR1CB and D_NR1CB.

Single: CALL NR1CB (N, A, LDA, NLCA, NUCA, ANORM)

Double: The double precision name is DNR1CB.

The routine NR1CB computes the 1-norm of a complex band matrix A. The 1-norm of a complex matrix A is

Compute the 1-norm of a complex matrix of order 4 in band storage mode.

USE NR1CB_INT

USE UMACH_INT

IMPLICIT NONE

! Declare variables

INTEGER LDA, N, NLCA, NUCA

PARAMETER (LDA=4, N=4, NLCA=2, NUCA=1)

INTEGER NOUT

REAL ANORM

COMPLEX A(LDA,N)

! Set values for A (in band mode)

! A = ( 0.0+0.0i 2.0+3.0i -1.0+1.0i -2.0-1.0i )

! ( -2.0+3.0i 1.0+0.0i -4.0-1.0i 0.0-4.0i )

! ( 2.0+2.0i 4.0+6.0i 3.0+2.0i 0.0+0.0i )

! ( 0.0-1.0i 2.0+1.0i 0.0+0.0i 0.0+0.0i )

DATA A/(0.0,0.0), (-2.0,3.0), (2.0,2.0), (0.0,-1.0), (2.0,3.0), &

(1.0,0.0), (4.0,6.0), (2.0,1.0), (-1.0,1.0), (-4.0,-1.0), &

(3.0,2.0), (0.0,0.0), (-2.0,-1.0), (0.0,-4.0), (0.0,0.0), &

(0.0,0.0)/

! Compute the L1 norm of A

CALL NR1CB (A, NLCA, NUCA, ANORM)

! Print results

CALL UMACH (2, NOUT)

WRITE (NOUT,*) ' The 1-norm of A is ', ANORM

END

Output

The 1-norm of A is 19.0000