code: def C3():
      n = 10
      A = torch.zeros(n, n)
      A.view(-1)[:: n + 1] = -2
      A.view(-1)[n :: n + 1] = 1
      A.view(-1)[1 :: n + 1] = 1
  
      def diffeq(t, y):
          return torch.mv(A, y)
  
      def init():
          y0 = torch.zeros(n)
          y0[0] = 1
          return torch.tensor(0.0), y0
  
      return diffeq, init, None
  
imports: import math
  import torch
label_desc: Use image node_id 13 for calling a global function with example usage: C3() and returns: diffeq,  init,  None, torch, torch,  y0