# Linear Solvers and Krylov Methods (KSP)
The `KSP` class provides an easy-to-use interface to the combination of
a Krylov subspace iterative method and a preconditioner `PC` for the solution of linear systems and some least squares problems. See
`PETSCREGRESSORLINEAR` for additional regression (least squares) solvers.
Examples
Source files
cgeig.c
cgimpl.h
cgtype.c
cg.c
cgls.c
Directories
cgne
gltr
groppcg
nash
pipecg
pipecg2
pipecgrr
pipelcg
pipeprcg
stcg