Fix preconditioning in cg when optional radius argument is positive
#1530
| Job | Run time |
|---|---|
| 7m 48s | |
| 10m 1s | |
| 11m 37s | |
| 8m 30s | |
| 9m 9s | |
| 8m 50s | |
| 13m 49s | |
| 11m 53s | |
| 12m 10s | |
| 1h 33m 47s |