petsc-3.7.3 2016-08-01
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TSAlpha2SetParams

 sets the algorithmic parameters for TSALPHA2

Synopsis

#include "petscts.h"   
PetscErrorCode TSAlpha2SetParams(TS ts,PetscReal alpha_m,PetscReal alpha_f,PetscReal gamma,PetscReal beta)
Logically Collective on TS

Second-order accuracy can be obtained so long as

\gamma = 1/2 + alpha_m - alpha_f \beta = 1/4 (1 + alpha_m - alpha_f)^2

Unconditional stability requires

\alpha_m >= \alpha_f >= 1/2

Input Parameter

ts - timestepping context
\alpha_m - algorithmic paramenter
\alpha_f - algorithmic paramenter
\gamma - algorithmic paramenter
\beta - algorithmic paramenter

Options Database

Note

Use of this function is normally only required to hack TSALPHA2 to use a modified integration scheme. Users should call TSAlpha2SetRadius() to set the desired spectral radius of the methods (i.e. high-frequency damping) in order so select optimal values for these parameters.

See Also

TSAlpha2SetRadius(), TSAlpha2GetParams()

Level:advanced
Location:src/ts/impls/implicit/alpha/alpha2.c
Index of all TS routines
Table of Contents for all manual pages
Index of all manual pages

-ts_alpha_alpha_m <alpha_m>- . -ts_alpha_alpha_f <alpha_f>
-ts_alpha_gamma <gamma>- - -ts_alpha_beta <beta>