organizing the docs - put the content in a content folder. put the SimPEG core api docs in core_api

docs/content/api_core/api_Solver.rst

@@ -0,0 +1,53 @@
+.. _api_Solver:
+
+
+Solver
+******
+
+BYOS
+====
+
+The numerical linear algebra solver that you use will ultimately be the
+bottleneck of your large scale inversion. To be the most flexible, SimPEG
+provides wrappers rather than a comprehensive set of solvers (i.e. BYOS).
+
+The interface is as follows::
+
+    A # Where A is a sparse matrix (or linear operator)
+    Ainv = Solver(A, **solverOpts) # Create a solver object with key word arguments
+    x = Ainv * b # Where b is a numpy array of shape (n,) or (n,*)
+    Ainv.clean() # This cleans the memory footprint (if any)
+
+.. note::
+
+    This is somewhat an abuse of notation for solvers as we never actually
+    create A inverse. Instead we are creating an object that acts like A
+    inverse, whether that be a Krylov subspace solver or an LU decomposition.
+
+To wrap up solvers in scipy.sparse.linalg it takes one line of code::
+
+
+    Solver   = SolverWrapD(sp.linalg.spsolve, factorize=False)
+    SolverLU = SolverWrapD(sp.linalg.splu, factorize=True)
+    SolverCG = SolverWrapI(sp.linalg.cg)
+
+.. note::
+
+    The above solvers are loaded into the base name space of SimPEG.
+
+.. seealso::
+
+    - https://bitbucket.org/petsc/petsc4py
+    - https://github.com/bfroehle/pymumps
+    - https://github.com/rowanc1/pymatsolver
+
+
+The API
+=======
+
+.. autofunction:: SimPEG.Utils.SolverUtils.SolverWrapD
+    :noindex:
+
+.. autofunction:: SimPEG.Utils.SolverUtils.SolverWrapI
+    :noindex:
+