gc_inout issue

[sxcgc]

Hi,
I found a bug in the pyngl when I used the gc_inout.

For example:

Ngl.gc_inout(30,120,[30,70,70,30,30],[120,120,160,160,120])
array([1], dtype=int32)
Ngl.gc_inout(31,120,[30,70,70,30,30],[120,120,160,160,120])
array([1], dtype=int32)
Ngl.gc_inout(31,121,[30,70,70,30,30],[120,120,160,160,120])
array([1], dtype=int32)
Ngl.gc_inout(30,121,[30,70,70,30,30],[120,120,160,160,120])
array([0], dtype=int32)

Obviously the point 30N 121E is in the box?
So why it is?

[rbrownrigg]

Hi, Its because gc_inout employs great circle computations. To see that, get out your globe and place a piece of string on it at two different points of the same latitude. Rick

…

On Sat, Dec 7, 2019 at 11:05 PM ustccgc ***@***.***> wrote: Hi, I found a bug in the pyngl when I used the gc_inout. For example: Ngl.gc_inout(30,120,[30,70,70,30,30],[120,120,160,160,120]) array([1], dtype=int32) Ngl.gc_inout(31,120,[30,70,70,30,30],[120,120,160,160,120]) array([1], dtype=int32) Ngl.gc_inout(31,121,[30,70,70,30,30],[120,120,160,160,120]) array([1], dtype=int32) Ngl.gc_inout(30,121,[30,70,70,30,30],[120,120,160,160,120]) array([0], dtype=int32) Obviously the point 30N 121E is in the box? So why it is? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#29?email_source=notifications&email_token=ADLWOXUSNILIOHB6AQZSPRLQXSFBJA5CNFSM4JXXL74KYY3PNVWWK3TUL52HS4DFUVEXG43VMWVGG33NNVSW45C7NFSM4H63ZGFQ>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADLWOXV7UUPLIJ6N53KMQDDQXSFBJANCNFSM4JXXL74A> .

[sxcgc]

But I can't understand the bug.

[rbrownrigg]

Well, again, it's not a bug, it employs great circle (shortest distance on a spherical earth model) computations.

…

On Tue, Dec 10, 2019 at 7:39 PM ustccgc ***@***.***> wrote: But I can't understand the bug. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#29?email_source=notifications&email_token=ADLWOXQPDSV5XXZMN6WIJHLQYBHHJA5CNFSM4JXXL74KYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEGRVDCA#issuecomment-564351368>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADLWOXUA6LFWW73WM6WARNLQYBHHJANCNFSM4JXXL74A> .

[sxcgc]

Oh, I understand it. Shortest distance is not along with the latitude.