Spectral Transformation - ST

## Spectral Transformation - ST: Examples

The Spectral Transformation (ST) class encapsulates the functionality required for acceleration techniques based on the transformation of the spectrum. As explained in the SLEPc Users Manual, the eigensolvers implemented in EPS work by applying an operator to a set of vectors and this operator can adopt different forms. The ST object handles all the different possibilities in a uniform way, so that the solver can proceed without knowing which transformation has been selected.

The type of spectral transformation can be specified at run time (e.g., `-st_type sinvert`) as well as several parameters such as the value of the shift (e.g., `-st_shift 1.5`).

ST objects are always related to EPS objects. Users should not create a standalone ST object. ST options can also be set directly in application codes by first extracting the ST context from the EPS context via EPSGetST() and then directly calling the ST routines (e.g., STSetType() / STSetShift()).

Beginner - Basic usage
| ST | STGetShift | STType
STCreate | STSetFromOptions | STView
STDestroy | STSetShift |
Intermediate - Setting options for algorithms and data structures
| STCayleyGetAntishift | STGetOperationCounters | STSetMatMode
STCayleySetAntishift | STGetOperators | STSetOperators
STGetKSP | STGetType | STSetType
STGetMatMode | STMatMode |
STGetNumMatrices | STResetOperationCounters |
Advanced - Setting more advanced options and customization
| STAppendOptionsPrefix | STRegister | STSetOptionsPrefix
STComputeExplicitOperator | STRegisterAll | STSetUp
STGetMatStructure | STReset | STShellGetContext
STGetOptionsPrefix | STSHELL | STShellSetContext
STPrecondGetMatForPC | STSetKSP |
STPrecondSetMatForPC | STSetMatStructure |
Developer - Interfaces intended primarily for library developers, not for typical applications programmers
| STApply | STInitializePackage | STPrecondSetKSPHasMat
STApplyTranspose | STMatMult | STSetBalanceMatrix
STBackTransform | STMatMultTranspose | STSetDefaultShift
STCheckNullSpace | STMatSolve | STShellSetApply
STFinalizePackage | STMatSolveTranspose | STShellSetApplyTranspose
STGetBalanceMatrix | STPostSolve | STShellSetBackTransform
STGetBilinearForm | STPrecondGetKSPHasMat |
No deprecated routines

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