{ diff(x1, t) = (1*k32*(1 - k25)*(k1*piecewise(1, t <= k31, 0) + k2) + (-1)*k32*k3*x1)/k32,
  diff(x2, t) = (1*k32*(1 - k25)*(k4*piecewise(1, t <= k31, 0) + k5) + (-1)*k32*k6*x4*x2*(1 - k26) + (-1)*k32*k7*x2)/k32,
  diff(x3, t) = (1*k32*k8*piecewise(1, t <= k31, 0) + 1*k32*k9 + (-1)*k32*k10*x3)/k32,
  diff(x4, t) = (1*k32*k11*piecewise(1, t <= k31, 0) + 1*k32*k12 + (-1)*k32*k13*x4)/k32,
  diff(x5, t) = (1*k32*k14*piecewise(1, t <= k31, 0)*x9 + 1*k32*piecewise(0, t <= k31, k30)*(1 - piecewise(1, t <= k31, 0))*x9 + (-1)*k32*k16*x4*(1 - k26)*x5 + (-1)*k32*k17*x5 + (-1)*k32*k18*x3*x5)/k32,
  diff(x6, t) = (1*k32*k18*x3*x5 + (-1)*k32*k19*x4*(1 - k26)*x6 + (-1)*k32*k20*x6*x2)/k32,
  diff(x7, t) = (1*k32*k16*x4*(1 - k26)*x5 + 1*k32*k19*x4*(1 - k26)*x6 + (-1)*k32*k21*x7 + (-1)*k32*k22*x1^2*x7)/k32,
  diff(x8, t) = (1*k32*k22*x1^2*x7 + (-1)*k32*k23*x8)/k32,
  diff(x9, t) = ((-1)*k32*k14*piecewise(1, t <= k31, 0)*x9 + (-1)*k32*piecewise(0, t <= k31, k30)*(1 - piecewise(1, t <= k31, 0))*x9 + 1*k32*k17*x5 + 1*k32*k20*x6*x2 + 1*k32*k21*x7 + 1*k32*k23*x8)/k32 }