Fix Lobatto exactness

Closes gh-162

Author: inducer

modepy/quadrature/jacobi_gauss.py

@@ -313,7 +313,7 @@ class JacobiGaussLobattoQuadrature(Quadrature):
 
         I[f] = \int_{-1}^1 f(x) (1 - x)^\alpha (1 + x)^\beta\, \mathrm{d}x,
 
-    There will be *N+1* nodes. Exact to degree :math:`2N - 3`.
+    There will be *N+1* nodes. Exact to degree :math:`2N - 1`.
 
     .. versionadded:: 2024.2
     """
@@ -382,7 +382,7 @@ def __init__(self,
         if force_dim_axis:
             nodes = nodes.reshape(1, -1)
 
-        super().__init__(nodes, weights, 2*N - 3)
+        super().__init__(nodes, weights, 2*N - 1)
 
 
 class LegendreGaussLobattoQuadrature(JacobiGaussLobattoQuadrature):