{ diff(x1, t) = ((-1)*k33*x12*x1*k26 + 1*(k12*166112956810631/100000000000000000*x2*x6 + (-k12*k13*x1))*k26)/k26,
  diff(x2, t) = (1*k33*x12*x1*k26 + (-1)*(k12*166112956810631/100000000000000000*x2*x6 + (-k12*k13*x1))*k26 + (-1)*k27*(k22*166112956810631/100000000000000000*x13*166112956810631/100000000000000000*x2 + (-k22*k23*166112956810631/100000000000000000*x5))*1*1/k1)/k27,
  diff(x3, t) = (-1)*k26*(piecewise(581/1000*k3*((-1) + exp((k2 + (-x7))*1/k2)), x7 < k2, 0) + piecewise(k4*exp(-(t + (-k5))*1/k6), t > k5, 0))*x3/k26,
  diff(x4, t) = 0,
  diff(x5, t) = 1*k27*(k22*166112956810631/100000000000000000*x13*166112956810631/100000000000000000*x2 + (-k22*k23*166112956810631/100000000000000000*x5))*1*1/k1/k27,
  diff(x6, t) = ((-1)*k30*x6*x12*k26 + (-1)*(k12*166112956810631/100000000000000000*x2*x6 + (-k12*k13*x1))*k26 + 1*k26*(piecewise(581/1000*k19*((-1) + exp((k18 + (-x6))*1/k18)), x6 < k18, 0) + piecewise(k15*exp(-(t + (-k16))*1/k17), t > k16, 0))*x7)/k26,
  diff(x7, t) = (1*k26*(piecewise(581/1000*k3*((-1) + exp((k2 + (-x7))*1/k2)), x7 < k2, 0) + piecewise(k4*exp(-(t + (-k5))*1/k6), t > k5, 0))*x3 + (-1)*k26*(piecewise(581/1000*k19*((-1) + exp((k18 + (-x6))*1/k18)), x6 < k18, 0) + piecewise(k15*exp(-(t + (-k16))*1/k17), t > k16, 0))*x7)/k26,
  diff(x8, t) = (1*k30*x6*x12*k26 + 1*k33*x12*x1*k26)/k26,
  diff(x9, t) = 0,
  diff(x10, t) = 0,
  diff(x11, t) = (-1)*k26*(k31*x11*k36*piecewise(exp(-(t + (-k9))*1/k10), t > k9, 0) + (-k32*x12))/k26,
  diff(x12, t) = 1*k26*(k31*x11*k36*piecewise(exp(-(t + (-k9))*1/k10), t > k9, 0) + (-k32*x12))/k26,
  diff(x13, t) = (1*k30*x6*x12*k26 + 1*k33*x12*x1*k26 + (-1)*k27*k35*(166112956810631/100000000000000000*x13 + (-k34))*1*1/k1 + (-1)*k27*(k22*166112956810631/100000000000000000*x13*166112956810631/100000000000000000*x2 + (-k22*k23*166112956810631/100000000000000000*x5))*1*1/k1)/k27 }