petsc-3.10.5 2019-03-28
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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

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

### 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

### Implementations

TSAlpha2SetParams_Alpha in src/ts/impls/implicit/alpha/alpha2.c
Index of all TS routines
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Index of all manual pages