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DSolve::dsvar NDSolve::dsvar NDSolveValue::dsvar ParametricNDSolve::dsvar ParametricNDSolveValue::dsvar RSolve::dsvar

DSolve::dsvar NDSolve::dsvar NDSolveValue::dsvar ParametricNDSolve::dsvar ParametricNDSolveValue::dsvar RSolve::dsvar

Details

  • This message is generated when the indicated expression cannot be used as a variable in DSolve, NDSolve, or RSolve.
  • Most expressions other than numbers, strings, products, sums, and powers can be used as variables.
  • The variable is specified in the third argument of DSolve or NDSolve for ordinary differential equations.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[DSolve::dsvar].

Examples

Basic Examples  (2)

A product cannot be used as a variable:

Wolfram Language code: DSolve[f'[2x] == 1, f, 2x]

The independent variable has been assigned a value previously:

Wolfram Language code: x = 5;
Wolfram Language code: DSolve[y'[x] == 1, y, x]

The solution is to clear :

Wolfram Language code: Clear[x]
Wolfram Language code: DSolve[y'[x] == 1, y, x]