# 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
lmbasis.c
lmbasis.h
lmproducts.c
lmproducts.h
lmvm.h
lmvmimpl.c
lmvmutils.c
Directories
bfgs
brdn
dense
dfp
diagbrdn
sr1
symbrdn
tests
blas_cyclic
rescale