updated iteration protocol

Author: lostella

src/bicgstabl.jl

@@ -1,6 +1,6 @@
 export bicgstabl, bicgstabl!, bicgstabl_iterator, bicgstabl_iterator!, BiCGStabIterable
 using Printf
-import Base: start, next, done
+import Base: iterate
 
 mutable struct BiCGStabIterable{precT, matT, solT, vecT <: AbstractVector, smallMatT <: AbstractMatrix, realT <: Real, scalarT <: Number}
     A::matT
@@ -76,7 +76,9 @@ end
 @inline start(::BiCGStabIterable) = 0
 @inline done(it::BiCGStabIterable, iteration::Int) = it.mv_products ≥ it.max_mv_products || converged(it)
 
-function next(it::BiCGStabIterable, iteration::Int)
+function iterate(it::BiCGStabIterable, iteration::Int=start(it))
+    if done(it, iteration) return nothing end
+
     T = eltype(it.x)
     L = 2 : it.l + 1
 

src/cg.jl

@@ -1,4 +1,4 @@
-import Base: start, next, done
+import Base: iterate
 using Printf
 export cg, cg!, CGIterable, PCGIterable, cg_iterator!, CGStateVariables
 
@@ -40,7 +40,9 @@ end
 # Ordinary CG #
 ###############
 
-function next(it::CGIterable, iteration::Int)
+function iterate(it::CGIterable, iteration::Int=start(it))
+    if done(it, iteration) return nothing end
+
     # u := r + βu (almost an axpy)
     β = it.residual^2 / it.prev_residual^2
     it.u .= it.r .+ β .* it.u
@@ -64,7 +66,12 @@ end
 # Preconditioned CG #
 #####################
 
-function next(it::PCGIterable, iteration::Int)
+function iterate(it::PCGIterable, iteration::Int=start(it))
+    # Check for termination first
+    if done(it, iteration)
+        return nothing
+    end
+
     ldiv!(it.c, it.Pl, it.r)
 
     ρ_prev = it.ρ

src/chebyshev.jl

@@ -1,4 +1,4 @@
-import Base: next, start, done
+import Base: iterate
 
 export chebyshev, chebyshev!
 
@@ -26,7 +26,9 @@ converged(c::ChebyshevIterable) = c.resnorm ≤ c.reltol
 start(::ChebyshevIterable) = 0
 done(c::ChebyshevIterable, iteration::Int) = iteration ≥ c.maxiter || converged(c)
 
-function next(cheb::ChebyshevIterable, iteration::Int)
+function iterate(cheb::ChebyshevIterable, iteration::Int=start(cheb))
+    if done(cheb, iteration) return nothing end
+
     T = eltype(cheb.x)
 
     ldiv!(cheb.c, cheb.Pl, cheb.r)

src/gmres.jl

@@ -1,4 +1,4 @@
-import Base: start, next, done
+import Base: iterate
 using Printf
 export gmres, gmres!
 
@@ -52,7 +52,8 @@ start(::GMRESIterable) = 0
 
 done(g::GMRESIterable, iteration::Int) = iteration ≥ g.maxiter || converged(g)
 
-function next(g::GMRESIterable, iteration::Int)
+function iterate(g::GMRESIterable, iteration::Int=start(g))
+    if done(g, iteration) return nothing end
 
     # Arnoldi step: expand
     expand!(g.arnoldi, g.Pl, g.Pr, g.k, g.Ax)

src/minres.jl

@@ -1,7 +1,7 @@
 export minres_iterable, minres, minres!
 using Printf
 import LinearAlgebra: BLAS.axpy!, givensAlgorithm
-import Base: start, next, done
+import Base: iterate
 
 mutable struct MINRESIterable{matT, solT, vecT <: DenseVector, smallVecT <: DenseVector, rotT <: Number, realT <: Real}
     A::matT
@@ -94,7 +94,9 @@ start(::MINRESIterable) = 1
 
 done(m::MINRESIterable, iteration::Int) = iteration > m.maxiter || converged(m)
 
-function next(m::MINRESIterable, iteration::Int)
+function iterate(m::MINRESIterable, iteration::Int=start(m))
+    if done(m, iteration) return nothing end
+
     # v_next = A * v_curr - H[2] * v_prev
     mul!(m.v_next, m.A, m.v_curr)
 

src/simple.jl

@@ -1,4 +1,4 @@
-import Base: start, next, done
+import Base: iterate
 
 #Simple methods
 export powm, powm!, invpowm, invpowm!
@@ -25,7 +25,8 @@ end
 
 @inline done(p::PowerMethodIterable, iteration::Int) = iteration > p.maxiter || converged(p)
 
-function next(p::PowerMethodIterable, iteration::Int)
+function iterate(p::PowerMethodIterable, iteration::Int=start(p))
+    if done(p, iteration) return nothing end
 
     mul!(p.Ax, p.A, p.x)
 

src/stationary.jl

@@ -1,7 +1,7 @@
 export jacobi, jacobi!, gauss_seidel, gauss_seidel!, sor, sor!, ssor, ssor!
 
 import LinearAlgebra.SingularException
-import Base: start, next, done, getindex
+import Base: getindex, iterate
 
 function check_diag(A::AbstractMatrix)
     for i = 1 : size(A, 1)
@@ -45,7 +45,9 @@ end
 
 start(::DenseJacobiIterable) = 1
 done(it::DenseJacobiIterable, iteration::Int) = iteration > it.maxiter
-function next(j::DenseJacobiIterable, iteration::Int)
+function iterate(j::DenseJacobiIterable, iteration::Int=start(j))
+    if done(j, iteration) return nothing end
+
     n = size(j.A, 1)
 
     copyto!(j.next, j.b)
@@ -103,7 +105,9 @@ end
 start(::DenseGaussSeidelIterable) = 1
 done(it::DenseGaussSeidelIterable, iteration::Int) = iteration > it.maxiter
 
-function next(s::DenseGaussSeidelIterable, iteration::Int)
+function iterate(s::DenseGaussSeidelIterable, iteration::Int=start(s))
+    if done(s, iteration) return nothing end
+
     n = size(s.A, 1)
 
     for col = 1 : n
@@ -160,7 +164,9 @@ end
 
 start(::DenseSORIterable) = 1
 done(it::DenseSORIterable, iteration::Int) = iteration > it.maxiter
-function next(s::DenseSORIterable, iteration::Int)
+function iterate(s::DenseSORIterable, iteration::Int=start(s))
+    if done(s, iteration) return nothing end
+
     n = size(s.A, 1)
 
     for col = 1 : n
@@ -218,7 +224,9 @@ end
 
 start(::DenseSSORIterable) = 1
 done(it::DenseSSORIterable, iteration::Int) = iteration > it.maxiter
-function next(s::DenseSSORIterable, iteration::Int)
+function iterate(s::DenseSSORIterable, iteration::Int=start(s))
+    if done(s, iteration) return nothing end
+
     n = size(s.A, 1)
 
     for col = 1 : n

src/stationary_sparse.jl

@@ -1,5 +1,5 @@
 import LinearAlgebra: mul!, ldiv!
-import Base: start, next, done, getindex
+import Base: getindex, iterate
 
 using SparseArrays
 
@@ -222,7 +222,8 @@ end
 
 start(::JacobiIterable) = 1
 done(j::JacobiIterable, iteration::Int) = iteration > j.maxiter
-function next(j::JacobiIterable{T}, iteration::Int) where {T}
+function iterate(j::JacobiIterable{T}, iteration::Int=start(j)) where {T}
+    if done(j, iteration) return nothing end
     # tmp = D \ (b - (A - D) * x)
     copyto!(j.next, j.b)
     mul!(-one(T), j.O, j.x, one(T), j.next)
@@ -273,7 +274,8 @@ end
 
 start(::GaussSeidelIterable) = 1
 done(g::GaussSeidelIterable, iteration::Int) = iteration > g.maxiter
-function next(g::GaussSeidelIterable, iteration::Int)
+function iterate(g::GaussSeidelIterable, iteration::Int=start(g))
+    if done(g, iteration) return nothing end
     # x ← L \ (-U * x + b)
     T = eltype(g.x)
     gauss_seidel_multiply!(-one(T), g.U, g.x, one(T), g.b, g.x)
@@ -316,7 +318,9 @@ end
 
 start(::SORIterable) = 1
 done(s::SORIterable, iteration::Int) = iteration > s.maxiter
-function next(s::SORIterable{T}, iteration::Int) where {T}
+function iterate(s::SORIterable{T}, iteration::Int=start(s)) where {T}
+    if done(s, iteration) return nothing end
+
     # next = b - U * x
     gauss_seidel_multiply!(-one(T), s.U, s.x, one(T), s.b, s.next)
 
@@ -384,7 +388,9 @@ end
 start(s::SSORIterable) = 1
 done(s::SSORIterable, iteration::Int) = iteration > s.maxiter
 
-function next(s::SSORIterable{T}, iteration::Int) where {T}
+function iterate(s::SSORIterable{T}, iteration::Int=start(s)) where {T}
+    if done(s, iteration) return nothing end
+
     # tmp = b - U * x
     gauss_seidel_multiply!(-one(T), s.sU, s.x, one(T), s.b, s.tmp)