:orphan:
# KSPLCD
Implements the LCD (left conjugate direction) method 
## Options Database Keys

- ***-ksp_lcd_restart -*** number of vectors conjugate
- ***-ksp_lcd_haptol -*** tolerance for exact convergence (happy ending)





## Note
Support only for left preconditioning


## References

- **** -*** J.Y. Yuan, G.H.Golub, R.J. Plemmons, and W.A.G. Cecilio. Semiconjugate
direction methods for real positive definite system. BIT Numerical
Mathematics, 44(1),2004.
- **** -*** Y. Dai and J.Y. Yuan. Study on semiconjugate direction methods for
nonsymmetric systems. International Journal for Numerical Methods in
Engineering, 60, 2004.
- **** -*** L. Catabriga, A.L.G.A. Coutinho, and L.P.Franca. Evaluating the LCD
algorithm for solving linear systems of equations arising from implicit
SUPG formulation of compressible flows. International Journal for
Numerical Methods in Engineering, 60, 2004
- **** -*** L. Catabriga, A. M. P. Valli, B. Z. Melotti, L. M. Pessoa,
A. L. G. A. Coutinho, Performance of LCD iterative method in the finite
element and finite difference solution of convection diffusion
equations,  Communications in Numerical Methods in Engineering, (Early
View).



## Contributed by
Lucia Catabriga <luciac@ices.utexas.edu>


## See Also
 [](ch_ksp), `KSPCreate()`, `KSPSetType()`, `KSPType`, `KSP`,
`KSPCGSetType()`, `KSPLCDSetRestart()`, `KSPLCDSetHapTol()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/lcd/lcd.c.html#KSPLCD">src/ksp/ksp/impls/lcd/lcd.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/ksp/impls/lcd/lcd.c)


[Index of all KSP routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)