snopt_integration.patch

diff --git a/torchdiffeq/_impl/adjoint.py b/torchdiffeq/_impl/adjoint.py
index ca9ba7f..001a53d 100644
--- a/torchdiffeq/_impl/adjoint.py
+++ b/torchdiffeq/_impl/adjoint.py
@@ -5,6 +5,8 @@ from .odeint import SOLVERS, odeint
 from .misc import _check_inputs, _flat_to_shape
 from .misc import _mixed_norm
 
+from snopt import SNOptAdjointCollector
+
 
 class OdeintAdjointMethod(torch.autograd.Function):
 
@@ -109,6 +111,8 @@ class OdeintAdjointMethod(torch.autograd.Function):
             #       Solve adjoint ODE        #
             ##################################
 
+            snopt_collector = SNOptAdjointCollector(func) if adjoint_options['use_snopt'] else None
+
             if t_requires_grad:
                 time_vjps = torch.empty(len(t), dtype=t.dtype, device=t.device)
             else:
@@ -123,9 +127,14 @@ class OdeintAdjointMethod(torch.autograd.Function):
                     time_vjps[i] = dLd_cur_t
 
                 # Run the augmented system backwards in time.
+                samp_t = t[i - 1:i + 1].flip(0)
+
+                if snopt_collector:
+                    adjoint_options, samp_t = snopt_collector.check_inputs(adjoint_options, samp_t)
+
                 aug_state = odeint(
                     augmented_dynamics, tuple(aug_state),
-                    t[i - 1:i + 1].flip(0),
+                    samp_t,
                     rtol=adjoint_rtol, atol=adjoint_atol, method=adjoint_method, options=adjoint_options
                 )
                 aug_state = [a[1] for a in aug_state]  # extract just the t[i - 1] value
diff --git a/torchdiffeq/_impl/solvers.py b/torchdiffeq/_impl/solvers.py
index 6915f2b..4a79f59 100644
--- a/torchdiffeq/_impl/solvers.py
+++ b/torchdiffeq/_impl/solvers.py
@@ -5,7 +5,7 @@ from .misc import _handle_unused_kwargs
 
 
 class AdaptiveStepsizeODESolver(metaclass=abc.ABCMeta):
-    def __init__(self, dtype, y0, norm, **unused_kwargs):
+    def __init__(self, dtype, y0, norm, snopt_collector=None, **unused_kwargs):
         _handle_unused_kwargs(self, unused_kwargs)
         del unused_kwargs
 
@@ -13,6 +13,7 @@ class AdaptiveStepsizeODESolver(metaclass=abc.ABCMeta):
         self.dtype = dtype
 
         self.norm = norm
+        self.snopt_collector = snopt_collector
 
     def _before_integrate(self, t):
         pass
@@ -28,6 +29,8 @@ class AdaptiveStepsizeODESolver(metaclass=abc.ABCMeta):
         self._before_integrate(t)
         for i in range(1, len(t)):
             solution[i] = self._advance(t[i])
+            if self.snopt_collector:
+                self.snopt_collector.call_invoke(self.func, t[i], solution[i])
         return solution
 
 
@@ -48,7 +51,7 @@ class AdaptiveStepsizeEventODESolver(AdaptiveStepsizeODESolver, metaclass=abc.AB
 class FixedGridODESolver(metaclass=abc.ABCMeta):
     order: int
 
-    def __init__(self, func, y0, step_size=None, grid_constructor=None, interp="linear", perturb=False, **unused_kwargs):
+    def __init__(self, func, y0, step_size=None, grid_constructor=None, interp="linear", perturb=False, snopt_collector=None, **unused_kwargs):
         self.atol = unused_kwargs.pop('atol')
         unused_kwargs.pop('rtol', None)
         unused_kwargs.pop('norm', None)
@@ -62,6 +65,7 @@ class FixedGridODESolver(metaclass=abc.ABCMeta):
         self.step_size = step_size
         self.interp = interp
         self.perturb = perturb
+        self.snopt_collector = snopt_collector
 
         if step_size is None:
             if grid_constructor is None:
@@ -113,6 +117,8 @@ class FixedGridODESolver(metaclass=abc.ABCMeta):
                     solution[j] = self._cubic_hermite_interp(t0, y0, f0, t1, y1, f1, t[j])
                 else:
                     raise ValueError(f"Unknown interpolation method {self.interp}")
+                if self.snopt_collector:
+                    self.snopt_collector.call_invoke(self.func, t[j], solution[j])
                 j += 1
             y0 = y1