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While trying to solve a system of coupled ODEs (for EVE[t] and FTZ[t]) with Manipulate, I keep getting a tremendous amount of errors, but I can't figure out why... among them, I get "NDSolve::ndnum: Encountered non-numerical value for a derivative at t == 0.", "ReplaceAll::reps: (...) is neither a list of replacement rules nor a valid dispatch table, and so cannot be used for replacing." and "NDSolve::dsvar: 0.004085714285714286 cannot be used as a variable.".

I don't understand why I get these errors since the time range I have seems to be reasonable, just as the initial conditions.

> (*** Initial conditions + free parameters ***)
tMax = 200;
eve0 = 2.0;
EVE0 = 2.0;
ftz0 = 2.0;
FTZ0 = 2.0;
d0 = 0.009; d1 = 2; d2 = 1; d3 = 4; d4 = 2; d5 = 4.0; d6 = 2.0; d7 = \
2.0; d8 = 2.0; 
(*Solving the system*)
Clear[sol2]
Manipulate[
 sol2 = NDSolve[{
    Derivative[1][EVE][t] == 
     d7 + E^(-t Subscript[k, 
        3]) (-d0 + d0 E^(t Subscript[k, 3]) + 
         eve0 Subscript[k, 3]) - (d3 EVE[t] Subscript[k, 13])/(
      d4 + FTZ[t] Subscript[k, 4] + EVE[t] Subscript[k, 13]) - (
      d5 EVE[t] Subscript[k, 1])/(
      d6 + EVE[t] Subscript[k, 1] + FTZ[t] Subscript[k, 15]),
    Derivative[1][FTZ][t] == 
     d8 + (E^(-d1 t) (-d2 + d2 E^(d1 t) + d1 ftz0) Subscript[k, 6])/
      d1 - (d3 FTZ[t] Subscript[k, 4])/(
      d4 + FTZ[t] Subscript[k, 4] + EVE[t] Subscript[k, 13]) - (
      d5 FTZ[t] Subscript[k, 15])/(
      d6 + EVE[t] Subscript[k, 1] + FTZ[t] Subscript[k, 15]),
    EVE[0] == EVE0, FTZ[0] == FTZ0}, {EVE, FTZ}, {t, 0, tMax}, 
   MaxSteps -> Infinity];

 Plot[{EVE[t], FTZ[t]} /. sol2, {t, 0, tMax}, PlotRange -> Full, 
  PlotStyle -> {Black}],
 {{k3, 0.01}, 0.00, 1.00}, {{k13, 0.01}, 0.00, 1.00}, {{k15, 0.01}, 
  0.00, 1.00}, {{k4, 0.01}, 0.00, 1.00}, {{k1, 0.01}, 0.00, 
  1.00}, {{k6, 0.01}, 0.00, 1.00}]

Thanks in advance! :)

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Remove the Subscripts!!!

Manipulate[sol2 = NDSolve[{Derivative[1][EVE][t] == d7 + E^(-t k3) (-d0 + d0 E^(t k3) + eve0 k3) - (d3 EVE[t] k13)/(d4 + FTZ[t] k4 + EVE[t] k13) - (d5 EVE[t] k1)/(d6 + EVE[t] k1 + FTZ[t] k15), Derivative[1][FTZ][t] == d8 + (E^(-d1 t) (-d2 + d2 E^(d1 t) + d1 ftz0) k6)/d1 - (d3 FTZ[t] k4)/(d4 + FTZ[t] k4 + EVE[t] k13)- (d5 FTZ[t] k15)/(d6 + EVE[t] k1 + FTZ[t] k15), EVE[0] == EVE0,FTZ[0] == FTZ0}, {EVE, FTZ}, {t, 0, tMax}, MaxSteps -> Infinity];
Plot[{EVE[t], FTZ[t]} /. sol2, {t, 0, tMax}, PlotRange -> Full,PlotStyle -> {Black}], 
{{k3, 0.01}, 0.00, 1.00}, {{k13, 0.01}, 0.00,1.00}, {{k15, 0.01}, 0.00, 1.00}, {{k4, 0.01}, 0.00, 1.00}, {{k1, 0.01}, 0.00,1.00}, {{k6, 0.01}, 0.00, 1.00}]

enter image description here

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  • $\begingroup$ that solved the problem, thank you!! $\endgroup$ – Beatriz A Jul 29 at 15:02

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