Posted by Dave Becker on July 20, 1997 at 21:54:12:

In the lanz.f package, symmetric sparse matrices are

packed according to diagonal elements, then off-diagonal elements

with accompanying lists of row and columns pointers.

I don't understand the definition of row pointers.

For an nxn symmetric matrix, the code expects n diagonal

elements, n+1 row pointers, and m column pointers.

For the following "sparse" matrix then,

| 1. 7.4 0. 0. 2.2 |

| 2. 0. 0.2 3.0 |

| 4. 7.1 0. |

| sym .3 .7 |

| 1.3 |

the n diagonals would be

1.

2.

4.

.3

1.3

the 6 off-diagonal elements:

7.4

2.2

0.2

3.0

7.1

0.7

the 6 column pointers would be

2

5

4

5

4

5

But what are the row pointers? It seems like there would

be only n-1 of them.

- Re: lanz
**Paul McMahan***09:52:46 7/21/97*(0)