CRBRG
Converts a real matrix in band storage mode to a real general matrix.
Required Arguments
A — Real (NUC + 1 + NLC) by N array containing the band matrix in band storage mode. (Input)
NLC — Number of lower codiagonals in A. (Input)
NUC — Number of upper codiagonals in A. (Input)
B — Real N by N array containing the matrix. (Output)
Optional Arguments
N — Order of the matrices A and B. (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).
LDB — Leading dimension of B exactly as specified in the dimension statement of the calling program. (Input)
Default: LDB = SIZE (B,1).
FORTRAN 90 Interface
Generic: CALL CRBRG (A, NLC, NUC, B [, …])
Specific: The specific interface names are S_CRBRG and D_CRBRG.
FORTRAN 77 Interface
Single: CALL CRBRG (N, A, LDA, NLC, NUC, B, LDB)
Double: The double precision name is DCRBRG.
Description
The routine CRBRG converts the real band matrix A of order N in band storage mode into the real N × N general matrix B with mu = NUC upper codiagonals and ml = NLC lower codiagonals. The first mu rows of A are copied to the upper codiagonals of B, the next row of A is copied to the diagonal of B, and the last ml rows of A are copied to the lower codiagonals of B.
Example
A real band matrix of order 3 in band storage mode with one upper codiagonal and one lower codiagonal is copied to a 3 × 3 real general matrix.
USE CRBRG_INT
USE WRRRN_INT
IMPLICIT NONE
! Declare variables
INTEGER LDA, LDB, N, NLC, NUC
PARAMETER (LDA=3, LDB=3, N=3, NLC=1, NUC=1)
!
REAL A(LDA,N), B(LDB,N)
! Set values for A (in band mode)
! A = ( 0.0 1.0 1.0)
! ( 4.0 3.0 2.0)
! ( 2.0 2.0 0.0)
!
DATA A/0.0, 4.0, 2.0, 1.0, 3.0, 2.0, 1.0, 2.0, 0.0/
! Convert band matrix A to matrix B
CALL CRBRG (A, NLC, NUC, B)
! Print results
CALL WRRRN ('B', B)
END
Output
B
1 2 3
1 4.000 1.000 0.000
2 2.000 3.000 1.000
3 0.000 2.000 2.000
Published date: 03/19/2020
Last modified date: 03/19/2020
