C.2.7. Subroutine FMSBW

PURPOSE

To compute the maximum, average and effective factoring bandwidths for use in estimating matrix storage and processing time.

SYNOPSIS


CALL FMSBW (LOWEQ, NUMEQ, BWMAX, BWAVG, BWEFF)

INPUT PARAMETERS

LOWEQ(NUMEQ) = Integer array.
Matrix profile vector that specifies the lowest coupled equation for each equation. For the lower triangular matrix [AL], this is the column number of the first non-zero term in each row. For the upper triangular matrix [AU], this is the row number of the first non-zero term in each column.
NUMEQ = Integer.
Number of equations in matrix [A].

OUTPUT PARAMETERS

BWMAX = Real.
Maximum bandwidth, computed from
```
MAX0(I - LOWEQ(I) + 1)
```
BWAVG = Real.
Average bandwidth, computed from
```
SUM(I - LOWEQ(I) + 1)/NUMEQ
```
BWEFF = Real.
Effective factoring bandwidth computed from the actual operation count of the factoring process.

DESCRIPTION:

This subroutine computes bandwidths that statistically describe the profile sparsity of the matrix. These bandwidths may be used to estimate the amount of processing time and storage requirements for the matrix.