Merge pull request #804 from LSSTDESC/omega_k_check

Added a check for the value of Omega_k.

pyccl/core.py

@@ -341,6 +341,10 @@ def _build_parameters(
             mu_0=None, sigma_0=None, z_mg=None, df_mg=None, Omega_g=None):
         """Build a ccl_parameters struct"""
 
+        # Check to make sure Omega_k is within reasonable bounds.
+        if Omega_k is not None and Omega_k < -1.0135:
+            raise ValueError("Omega_k must be more than -1.0135.")
+
         # Set nz_mg (no. of redshift bins for modified growth fns.)
         if z_mg is not None and df_mg is not None:
             # Get growth array size and do sanity check

pyccl/tests/test_parameters.py

@@ -508,3 +508,9 @@ def test_parameters_read_write():
         IOError,
         params.read_yaml,
         filename=temp_file_name+"/nonexistent_directory/params.yml")
+
+
+def test_omega_k():
+    """ Check that the value of Omega_k is within reasonable bounds. """
+    assert_raises(ValueError, ccl.Cosmology, Omega_c=0.25, Omega_b=0.05, h=0.7,
+                  A_s=2.1e-9, n_s=0.96, Omega_k=-2)