Add/expand docstrings

QuantumKitHub · Jan 21, 2025 · 3a1534f · 3a1534f
1 parent 68f72b4
commit 3a1534f
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 4 deletions.
diff --git a/src/algorithms/ED.jl b/src/algorithms/ED.jl
@@ -1,5 +1,13 @@
 """
-Use krylovkit to perform exact diagonalization
+    exact_diagonalization(opp::FiniteMPOHamiltonian;
+                          sector=first(sectors(oneunit(physicalspace(opp, 1)))),
+                          len::Int=length(opp), num::Int=1, which::Symbol=:SR,
+                          alg=Defaults.alg_eigsolve(; dynamic_tols=false))
+                            -> vals, state_vecs, convhist
+
+Use [`KrylovKit.eigsolve`](@extref) to perform exact diagonalization on a
+`FiniteMPOHamiltonian` to find its eigenvectors as `FiniteMPS` of maximal rank, essentially
+equivalent to dense eigenvectors.
 """
 function exact_diagonalization(opp::FiniteMPOHamiltonian;
                                sector=first(sectors(oneunit(physicalspace(opp, 1)))),

diff --git a/src/algorithms/fidelity_susceptibility.jl b/src/algorithms/fidelity_susceptibility.jl
@@ -1,6 +1,17 @@
-#=
-I don't know if I should rescale by system size / unit cell
-=#
+"""
+    fidelity_susceptibility(state::Union{FiniteMPS,InfiniteMPS}, H₀::T,
+                            Vs::AbstractVector{T}, [henvs=environments(state, H₀)];
+                            maxiter=Defaults.maxiter,
+                            tol=Defaults.tol) where {T<:MPOHamiltonian}
+
+Computes the fidelity susceptibility of a the ground state `state` of a base Hamiltonian
+`H₀` with respect to a set of perturbing Hamiltonians `Vs`. Each of the perturbing
+Hamiltonians can be interpreted as corresponding to a tuning parameter ``aᵢ`` in a 'total'
+Hamiltonian ``H = H₀ + ∑ᵢ aᵢ Vᵢ``.
+
+Returns a matrix containing the overlaps of the elementary excitations on top of `state`
+corresponding to each of the perturbing Hamiltonians.
+"""
 function fidelity_susceptibility(state::Union{FiniteMPS,InfiniteMPS}, H₀::T,
                                  Vs::AbstractVector{T}, henvs=environments(state, H₀);
                                  maxiter=Defaults.maxiter,