[petsc-dev] TS Terminology

[Jed Brown]

"Zhang, Hong" <hongzhang at anl.gov> writes:

> Another confusion which is not related to this topic is the usage of the word "DAE".
> I disagree with the statement "In general, this (the general form) is a differential algebraic equation (DAE)" on page 141 of the manual.
> The word "DAE" has been abused in the comments of many TS functions (including TSComputeIFunction), where it actually should mean "DAE or ODE".
> PETSc uses the same interfaces for both DAE and ODE, but it is wrong to consider ODE as a special case of DAE.
> They are fundamentally different from each other and should be distinguished explicitly in the manual and the source code.

Is this not valid usage?

  "Thus, ODEs have index 0."

  http://www.scholarpedia.org/article/Differential-algebraic_equations