Fixes wrapping issue for 2pi CAR maps (#222)

* fixed wrapping

* test data

pymaster/tests/test_field_car.py

@@ -4,6 +4,8 @@
 import sys
 import pytest
 from .utils import normdiff
+from astropy.io import fits
+from astropy.wcs import WCS
 
 
 class FieldTesterCAR(object):
@@ -13,9 +15,6 @@ def __init__(self):
         if (sys.version_info > (3, 1)):
             warnings.simplefilter("ignore", ResourceWarning)
 
-        from astropy.io import fits
-        from astropy.wcs import WCS
-
         hdul = fits.open("test/benchmarks/mps_car_small.fits")
         self.wcs = WCS(hdul[0].header)
         self.ny, self.nx = hdul[0].data.shape
@@ -238,3 +237,14 @@ def test_field_error():
         nmt.NmtField(FT.msk, [FT.mps[0]],
                      templates=[[t[0]] for t in FT.tmp],
                      beam=1, wcs=FT.wcs)
+
+
+def test_field_car_wrap():
+    # Tests that full-sky maps that could wrap around azimuth
+    # with floating point errors in `cdelt` are still parseable.
+
+    hdul = fits.open("test/benchmarks/car_wrap.fits")
+    wcs = WCS(hdul[0].header)
+    m = hdul[0].data
+    # This should throw no error
+    nmt.NmtField(m[0], [m[0]], wcs=wcs)

pymaster/utils.py

@@ -154,7 +154,7 @@ def from_rectpix(cls, n_theta, theta_min, d_theta,
         theta = th[:-1].astype(np.float64)
         phi0 = np.zeros(n_theta, dtype=np.float64)+phi0
         nx_short = n_phi
-        nx_full = int(2*np.pi/d_phi)
+        nx_full = int(2*np.pi/d_phi+0.5)
         nphi = np.zeros(n_theta, dtype=np.uint64)+nx_full
 
         # CC weights according to ducc0