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NDSolve::ndstf NDSolveValue::ndstf ParametricNDSolve::ndstf ParametricNDSolveValue::ndstf

NDSolve::ndstf NDSolveValue::ndstf ParametricNDSolve::ndstf ParametricNDSolveValue::ndstf

Details

  • This message indicates that the system appears to be stiff, but a numerical method not suited for dealing with stiff systems has been chosen.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[NDSolve::ndstf].

Examples

Basic Examples  (1)

An unfortunate method choice leads to the message:

Wolfram Language code: eqns = {Derivative[1][Subscript[Y, 1]][T] == -(1/25) Subscript[Y, 1][T] + 10000 Subscript[Y, 2][T] Subscript[Y, 3][T], Derivative[1][Subscript[Y, 2]][T] == (Subscript[Y, 1][T]/25) - 30000000 Subscript[Y, 2][T]^2 - 10000 Subscript[Y, 2][T] Subscript[Y, 3][T], Derivative[1][Subscript[Y, 3]][T] == 30000000 Subscript[Y, 2][T]^2}; conds = {Subscript[Y, 1][0] == 1, Subscript[Y, 2][0] == 0, Subscript[Y, 3][0] == 0}; NDSolve[{eqns, conds}, {Subscript[Y, 1][T], Subscript[Y, 2][T], Subscript[Y, 3][T]}, {T, 0, 3 / 10}, Method -> "ExplicitRungeKutta"];

The system appears to be stiff at the given point, and Method "StiffnessSwitching" should help:

Wolfram Language code: NDSolve[{eqns, conds}, {Subscript[Y, 1][T], Subscript[Y, 2][T], Subscript[Y, 3][T]}, {T, 0, 3 / 10}, Method -> "StiffnessSwitching"]

In fact, the Automatic method is often able to identify that the system is stiff and use "StiffnessSwitching" automatically:

Wolfram Language code: NDSolve[{eqns, conds}, {Subscript[Y, 1][T], Subscript[Y, 2][T], Subscript[Y, 3][T]}, {T, 0, 3 / 10}]