# Matrix Operations (Mat)
PETSc matrices (`Mat` objects) are used to store Jacobians and other sparse matrices
in PDE-based (or other) simulations. Users guide chapter: [](ch_matrices). See also [](../MatGraphOperations/index).
Examples
Directories
f90-mod
ftn-custom
ftn-kernels
graphops
impls
interface
matfd
tests
tutorials
utils