Coordinate conversion gives wrong results

[pjacklam]

Description

The Coordinate Converter tool gives wrong results. For example, the input "N 59.99999 E 12.99999" gives

DDM: N05 10.000 E001 03.000
DMS: N05° 09' 60.00" E001° 02' 60.00"
DD: 5.16667, 1.05000

Not only is the degrees wrong, but the output also allows the value 60 for the seconds. I had a look at src/opensak/coords.py, and several functions return rounded values directly. However, after rounding, the rounded value should be checked to see if it has the value 60. Of course, when the rounded value for seconds is 60, the seconds should be set to 0, and the minutes should be incremented. Ditto for minutes and degrees.

Steps to Reproduce

• Click "Tools"
• Click "Coordinate Converter…"
• Paste "N 59.99999 E 12.99999"

Expected Behavior

I expect "N 59.99999 E 12.99999" to return

DDM: N59° 59.999' E012° 59.999'
DMS: N59° 59' 59.96" E012° 59' 59.96"
DD: 59.99999, 12.99999

And I expect "N 59.999999 E 12.999999" to return

DDM: N60° 00.000' E013° 00.000'
DMS: N60° 00' 00.00" E013° 00' 00.00"
DD: 60.00000, 13.00000

Environment

OS: Windows 11
OpenSAK version 1.17.0

[AgreeDK]

Thanks for raising this, i will look at it to get it fixed.

[pjacklam]

Thanks for raising this, i will look at it to get it fixed.

I know maths, so had I been a better Python programmer, I would have fixed it myself and submitted a pull request.

[AgreeDK]

Fixed in v1.17.1-beta.8.

Root cause turned out to be two independent bugs in src/opensak/coords.py:

Parsing: parse_coords() had no dedicated branch for a plain decimal-degree value written with a hemisphere letter instead of a +/- sign (e.g. "N 59.99999 E 12.99999", no separate minutes component). It fell through to the DMM° regex branch instead, where backtracking let the degrees group give back digits to the minutes group whenever keeping them would leave an unparseable "." right after — silently reinterpreting "59.99999" as degrees=5, minutes=9.99999 (5.16667° instead of 59.99999°), with no error shown. This explains the wildly wrong degree value in the original report.
Rounding carry: exactly as you diagnosed — _dd_to_dmm()/_dd_to_dms() rounded minutes/seconds directly without checking whether the rounded value hit 60, so e.g. 59.999999° displayed as "59° 60.000'" instead of carrying into "60° 00.000'". The cache list's own Lat/Lon columns (format_lat()/format_lon()) had the exact same bug independently, so that's fixed too — not just the standalone converter tool.

Verified against both of your exact examples end-to-end; output now matches what you expected in every field.

Thanks for reading through coords.py yourself and pointing at the exact rounding issue — saved a lot of diagnostic time.