Usage:
$ rowcalc --dist 14000 --time 60 --by-dist 1000
time per 500m: 2m09s
split dist time
1. 1000 257s
2. 2000 514s
3. 3000 771s
4. 4000 1029s
5. 5000 1286s
6. 6000 1543s
7. 7000 1800s
8. 8000 2057s
9. 9000 2314s
10. 10000 2571s
11. 11000 2829s
12. 12000 3086s
13. 13000 3343s
14. 14000 3600s
$ rowcalc --dist 14000 --time 60 --by-time 300
time per 500m: 2m09s
split dist time
1. 1167 300s
2. 2333 600s
3. 3500 900s
4. 4667 1200s
5. 5833 1500s
6. 7000 1800s
7. 8167 2100s
8. 9333 2400s
9. 10500 2700s
10. 11667 3000s
11. 12833 3300s
12. 14000 3600s