petsc-3.14.5 2021-03-03
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# TSAlphaSetRadius

sets the desired spectral radius of the method (i.e. high-frequency numerical damping)

### Synopsis

    #include "petscts.h"
    PetscErrorCode TSAlphaSetRadius(TS ts,PetscReal radius)

Logically Collective on TS

The algorithmic parameters \alpha_m and \alpha_f of the generalized-\alpha method can be computed in terms of a specified spectral radius \rho in [0,1] for infinite time step in order to

### control high-frequency numerical damping

\alpha_m = 0.5*(3-\rho)/(1+\rho) \alpha_f = 1/(1+\rho)

### Input Parameter

| ts | - timestepping context
| radius | - the desired spectral radius

### Options Database

| -ts_alpha_radius <radius>

### See Also

TSAlphaSetParams(), TSAlphaGetParams()

### Level

intermediate

### Location

src/ts/impls/implicit/alpha/alpha1.c

### Implementations

TSAlphaSetRadius_Alpha in src/ts/impls/implicit/alpha/alpha1.c
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Index of all manual pages