llcrnrlon vs llcrnrx [-180, 180 vs 0, 360]

Personne n'a encore pris cette issue.

I was playing with the projections and it took me a while to understand what's going on... I need the `'rotpole'` projection to convert some locations and plot some graphs. I have all the information: `lon_0 = 10, o_lon_p = 10, o_lat_p = 10`, but I don't have the real lat/lon, I have the rotated one so I'm forced to use `llcrnrx, llcrnry...`.

I have a climate model that gives me the output in this rotated pole projection with rotated left lon = -19.5, rotated right lon = 21, rotated bottom lat = -25, rotated top lat = 20.5.

First take:

``` python
import mpl_toolkits.basemap as mb
kwargs = {
'projection': 'rotpole',
'llcrnrx': -19.5,
'llcrnry': -25,
'urcrnrx': 21,
'urcrnry': 20.5,
'o_lon_p': 10,
'o_lat_p': 32.5,
'lat_0': 10
}
m = mb.Basemap(**kwargs)
```

Now `m.drawcoastlines()` will give me a huge map that goes backwards on X axis... After a full day of investigation... I saw that `m.llcrnrx' takes the value of`360-19.5 = 340.5`and`m.urcrnrx = 21` so this clearly dosn't work...


Is this behaviour wanted? I mean, when building `m = mb.Basemap(...)` using `llcrnrlon, llcrnrlat...` you can safely pass negative values to `llcrnrlon` but when using `llcrnrx` you're forced to use `(0, 360)`...

Working version is:

``` python
import mpl_toolkits.basemap as mb
kwargs = {
'projection': 'rotpole',
'llcrnrx': 0,
'llcrnry': -25,
'urcrnrx': 21,
'urcrnry': 40.5,
'o_lon_p': 10,
'o_lat_p': 32.5,
'lat_0': -9.5
}
m = mb.Basemap(**kwargs)
```

So now I'm forced to do:

``` python
# x, y taken from climate model
xoffset = 19.5
lon, lat = m([x + xoffset], [y], inverse=True)
```

Even more confusing is the fact that you can use negative values in convert as in `m(-1, 0, inverse=True)` and you get the correct negative real longitude value...

_Edit_: using version 1.0.7; fixed `'urcrnry'` misspell

Commencez par reproduire les exemples fournis du constructeur Basemap et de conversion inverse avec les coordonnées du pôle pivoté signalées. Examinez la manière dont le point d’entrée de Basemap gère les plages llcrnrx et urcrnrx, déterminez ensuite le comportement attendu des coordonnées et ajoutez une couverture pour le cas d’une longitude pivotée négative. La tâche est terminée lorsque la plage de coordonnées documentée et l’orientation de carte obtenue sont cohérentes.

Rédigé par le modèle d'indexation à partir du texte de l'issue.