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DSolve::conarg NDSolve::conarg NDSolveValue::conarg ParametricNDSolve::conarg ParametricNDSolveValue::conarg RSolve::conarg

DSolve::conarg NDSolve::conarg NDSolveValue::conarg ParametricNDSolve::conarg ParametricNDSolveValue::conarg RSolve::conarg

Details

  • This message is generated when the function arguments in the specification of an equation occur in different orders in different parts of the equation.
  • The cause of this error can in most cases be readily identified by inspecting the input to be sure that the solution function is always specified in the same way.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[DSolve::conarg].

Examples

Basic Examples  (2)

The arguments of the solution function are not ordered consistently:

Wolfram Language code: NDSolve[{D[f[x, t], x, x] == D[f[t, x], t], f[0, t] == 0, f[1, t] == 0, f[x, 0] == x(x - 1)}, f, {x, 0, 1}, {t, 0, 1}]

This shows a correct specification of the partial differential equation:

Wolfram Language code: NDSolve[{D[f[x, t], x, x] == D[f[x, t], t], f[0, t] == 0, f[1, t] == 0, f[x, 0] == x(x - 1)}, f, {x, 0, 1}, {t, 0, 1}]

Dependent variables need to be grouped together:

Wolfram Language code: eqns = { x''[t] + 3.44 x[t] == 10 ^ -6, y''[t] + 3.44y[t] == 0.5 10 ^ -7, x[0] == 1., x'[0] == 0, y[0] == 0., y'[0] == 0.5}; NDSolve[eqns , x[t], y[t], { t, 0, 10} ]

In the list of variables, and are not grouped together. It should be written as :

Wolfram Language code: NDSolve[eqns , {x[t], y[t]}, { t, 0, 10} ]