reduce quad grid number of radial points to match intended functional…

…ity and not oversample unnecessarily

desc/grid.py

@@ -1243,7 +1243,9 @@ def _create_nodes(self, L=1, M=1, N=1, NFP=1):
         self._N = check_nonnegint(N, "N", False)
         self._NFP = check_posint(NFP, "NFP", False)
         self._period = (np.inf, 2 * np.pi, 2 * np.pi / self._NFP)
-        L = L + 1
+        # divide (L+1) by 2 bc only need (L+1)/2  points to
+        # integrate L-th order jacobi polynomial exactly
+        L = round((L + 1) / 2)
         M = 2 * M + 1
         N = 2 * N + 1
 

tests/test_grid.py

@@ -482,14 +482,14 @@ def test_quadrature_grid(self):
         N = 0
         NFP = 1
         grid_quad = QuadratureGrid(L, M, N, NFP)
-        roots, weights = special.js_roots(3, 2, 2)
+        roots, weights = special.js_roots(2, 2, 2)
         quadrature_nodes = np.stack(
             [
-                np.array([roots[0]] * 5 + [roots[1]] * 5 + [roots[2]] * 5),
+                np.array([roots[0]] * 5 + [roots[1]] * 5),
                 np.array(
-                    [0, 2 * np.pi / 5, 4 * np.pi / 5, 6 * np.pi / 5, 8 * np.pi / 5] * 3
+                    [0, 2 * np.pi / 5, 4 * np.pi / 5, 6 * np.pi / 5, 8 * np.pi / 5] * 2
                 ),
-                np.zeros(15),
+                np.zeros(10),
             ]
         ).T
         np.testing.assert_allclose(grid_quad.spacing.prod(axis=1), grid_quad.weights)