Doc update NTK

docs/source/_rst/_code.rst

@@ -248,3 +248,4 @@ Losses and Weightings
     PowerLoss <loss/powerloss.rst>
     WeightingInterface <loss/weighting_interface.rst>
     ScalarWeighting <loss/scalar_weighting.rst>
+    NeuralTangentKernelWeighting <loss/ntk_weighting.rst>

pina/loss/ntk_weighting.py

@@ -17,9 +17,7 @@ class NeuralTangentKernelWeighting(WeightingInterface):
         Paris Perdikaris. *When and why PINNs fail to train:
         A neural tangent kernel perspective*. Journal of
         Computational Physics 449 (2022): 110768.
-        DOI: `10.1016/j.jcp.2021.110768 <https://doi.org/10.1016/j.jcp.2021.110768>`_.
-
-
+        DOI: `10.1016 <https://doi.org/10.1016/j.jcp.2021.110768>`_.
 
     """
 
@@ -29,6 +27,8 @@ def __init__(self, model, alpha=0.5):
 
         :param torch.nn.Module model: The neural network model.
         :param float alpha: The alpha parameter.
+
+        :raises ValueError: If ``alpha`` is not between 0 and 1 (inclusive).
         """
 
         super().__init__()
@@ -43,7 +43,7 @@ def __init__(self, model, alpha=0.5):
 
     def aggregate(self, losses):
         """
-        Weights the losses according to the Neural Tangent Kernel
+        Weight the losses according to the Neural Tangent Kernel
         algorithm.
 
         :param dict(torch.Tensor) input: The dictionary of losses.