Surprising ang2pix results #73
Description
Hello,
Firstly - great work on this! I'm currently working on using it as the HEALPix engine in cf-python - thank you.
I've noticed some surprising results with ang2pix in some cases:
import healpix
for lat in ([89.9], [0.01], [0]):
i = healpix.ang2pix(2, [0, 45, 90, 135, 180, 225, 270, 315], lat, nest=True, lonlat=True)
print('lat=',lat,'result=', i)gives
lat= [89] result= [ 9 3 13 7 17 11 21 15] # Not OK: Didn't expect 9, 13, 17, 21
lat= [0.01] result= [19 0 23 4 27 8 31 12] # OK
lat= [0] result= [19 28 23 32 27 36 31 24] # Not OK: Didn't expect 32, 36
# Expected one of 0, 17, 22, 35
# Expected one of 4, 21, 26, 36
# Expected one of 8, 25, 30, 43
# Expected one of 12, 18, 29, 47It'd be great to know ...
- Am I using the library correctly?
- Are my expectations correct on this?
Many thanks for your help,
David
Here's the Górski figure for reference:
