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# STPRECOND

STPRECOND = “precond” - A special type of `ST` intended for use with preconditioned eigensolvers.

## Note

This is not a true spectral transformation. It behaves as an “inexact” version of the `STSINVERT` operator, in the sense that the associated `KSP` and `PC` objects can be used to implement a preconditioner \(K^{-1}\approx(A-\sigma B)^{-1}\) in the context of preconditioned eigensolvers such as Jacobi-Davidson.

## See Also

ST: Spectral Transformation, `ST`, `STType`, `STSetType()`, `STSetMatrices()`, `STSetShift()`

## Level

beginner

## Location

src/sys/classes/st/impls/precond/precond.c

Index of all ST routines Table of Contents for all manual pages Index of all manual pages