TSAlphaSetParams#

sets the algorithmic parameters for TSALPHA

Synopsis#

#include "petscts.h"   
PetscErrorCode TSAlphaSetParams(TS ts, PetscReal alpha_m, PetscReal alpha_f, PetscReal gamma)

Logically Collective

Second-order accuracy can be obtained so long as#

\gamma = 0.5 + alpha_m - alpha_f

Unconditional stability requires#

\alpha_m >= \alpha_f >= 0.5

Backward Euler method is recovered with#

\alpha_m = \alpha_f = gamma = 1

Input Parameters#

ts - timestepping context
alpha_m - algorithmic parameter
alpha_f - algorithmic parameter
gamma - algorithmic parameter

Options Database Keys#

-ts_alpha_alpha_m <alpha_m> - set alpha_m
-ts_alpha_alpha_f <alpha_f> - set alpha_f
-ts_alpha_gamma - set gamma

Note#

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