Documenting CGStateVariables

Author: mohamed82008

src/cg.jl

@@ -90,6 +90,16 @@ end
 
 # Utility functions
 
+"""
+Intermediate CG state variables to be used inside cg and cg!. `u`, `r` and `c` should be of the same type as the solution of `cg` or `cg!`.
+```
+struct CGStateVariables{T,Tx<:AbstractArray{T}}
+    u::Tx
+    r::Tx
+    c::Tx
+end
+```
+"""
 struct CGStateVariables{T,Tx<:AbstractArray{T}}
     u::Tx
     r::Tx
@@ -154,15 +164,16 @@ cg(A, b; kwargs...) = cg!(zerox(A, b), A, b; initially_zero = true, kwargs...)
 
 ## Keywords
 
+- `statevars::CGStateVariables`: Has 3 arrays similar to `x` to hold intermediate results;
 - `initially_zero::Bool`: If `true` assumes that `iszero(x)` so that one 
   matrix-vector product can be saved when computing the initial 
   residual vector;
 - `Pl = Identity()`: left preconditioner of the method. Should be symmetric, 
-  positive-definite like `A`.
+  positive-definite like `A`;
 - `tol::Real = sqrt(eps(real(eltype(b))))`: tolerance for stopping condition `|r_k| / |r_0| ≤ tol`;
 - `maxiter::Int = size(A,2)`: maximum number of iterations;
 - `verbose::Bool = false`: print method information;
-- `log::Bool = false`: keep track of the residual norm in each iteration;
+- `log::Bool = false`: keep track of the residual norm in each iteration.
 
 # Output