/usr/share/circos/tools/matrix/matrix.width.txt is in circos-tools 0.22-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 | 1 a 1a
1 b 1b
2 a 2a
2 d 2d
3 b 3b
4 c 4c
5 a 5a
10 b 10b
15 d 15d
30 a 30a
30 c 30c
30 d 30d
|