petsc-3.14.6 2021-03-30
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sets function to transform from state to transient variables


#include "petscts.h"  
PetscErrorCode TSSetTransientVariable(TS ts,TSTransientVariable tvar,void *ctx)
Logically Collective

Input Arguments

ts - time stepping context on which to change the transient variable
tvar - a function that transforms to transient variables
ctx - a context for tvar

Calling sequence of tvar

    PetscErrorCode tvar(TS ts,Vec p,Vec c,void *ctx);

ts - timestep context
p - input vector (primative form)
c - output vector, transient variables (conservative form)
ctx - [optional] user-defined function context


This is typically used to transform from primitive to conservative variables so that a time integrator (e.g., TSBDF) can be conservative. In this context, primitive variables P are used to model the state (e.g., because they lead to well-conditioned formulations even in limiting cases such as low-Mach or zero porosity). The transient variable is C(P), specified by calling this function. An IFunction thus receives arguments (P, Cdot) and the IJacobian must be evaluated via the chain rule, as in

dF/dP + shift * dF/dCdot dC/dP.

See Also

DMTSSetTransientVariable(), DMTSGetTransientVariable(), TSSetIFunction(), TSSetIJacobian()




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Index of all manual pages