NDSolve::ibcinc NDSolveValue::ibcinc ParametricNDSolve::ibcinc ParametricNDSolveValue::ibcinc

Details

  • This message is generated when the boundary conditions and initial conditions in a partial differential equation give different values for the solution at a single point.
  • Difficulties with inconsistent boundary and initial conditions can sometimes be resolved by approximating the inconsistent conditions with consistent conditions.
  • Although inconsistent boundary and initial conditions are common in practical models, such conditions generally represent unphysical processes, such as an instantaneous change in temperature, and can lead to singular solutions that may be difficult to handle by numerical methods.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[NDSolve::ibcinc].

Examples

Basic Examples  (2)

A warning is generated because the initial conditions and boundary conditions give two different values for the value of f[0,0]. This example corresponds to a heat equation in which the temperature at one endpoint changes instantly:

One way to avoid the inconsistent conditions on the solution is to replace the discontinuous condition with a similar condition that changes quickly but smoothly:

This shows a plot of the solution:

Clear the value of sol:

When the spatial discretization is too coarse, the message may be issued even though the conditions are actually consistent:

This behavior is expected and explained in "Inconsistent Boundary Conditions". Refining the spatial discretization sufficiently eliminates the message: