NDSolve::pdord
NDSolveValue::pdord
ParametricNDSolve::pdord
ParametricNDSolveValue::pdord
NDSolve::pdord NDSolveValue::pdord ParametricNDSolve::pdord ParametricNDSolveValue::pdord
Details
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- This message is generated when the equations do not include derivatives of one or more of the functions specified in the second argument of NDSolve.
- This message does not necessarily indicate an error.
- Off[message] switches off the message; On[message] switches it on. For example: Off[NDSolve::pdord].
Examples
Basic Examples (2)
A warning message is generated because there are no derivatives of y[t] in the equations:
NDSolve[{x'[t] == 2 y[t], x'[t] == 1 - y[t], x[0] == 1}, {x, y}, {t, 0, 1}]
Here, λ[t] appears with no derivative. Therefore, the equations will be solved as a differential-algebraic equation. The message is just a warning:
eqns = {x''[t] + λ[t] x[t] == 0, y''[t] + λ[t] y[t] == -1, D[x[t] ^ 2 + y[t] ^ 2 == 1, {t, 2}]};
conds = {x[0] == 1, x'[0] == 0, x''[0] == 0, y[0] == 0, y'[0] == 0, y''[0] == -1, λ[0] == 0};
d2sol = NDSolve[{eqns, conds}, {x, y, λ}, {t, 0, 100}]