define maxiters similar to epochs

lib/OptimizationOptimisers/src/OptimizationOptimisers.jl

@@ -9,11 +9,13 @@ SciMLBase.requiresgradient(opt::AbstractRule) = true
 SciMLBase.allowsfg(opt::AbstractRule) = true
 
 function SciMLBase.__init(
-        prob::SciMLBase.OptimizationProblem, opt::AbstractRule; save_best = true,
-        callback = (args...) -> (false), epochs = nothing,
-        progress = false, kwargs...)
-    return OptimizationCache(prob, opt; save_best, callback, progress, epochs,
-        kwargs...)
+        prob::SciMLBase.OptimizationProblem, opt::AbstractRule;
+        callback = (args...) -> (false),
+        epochs::Union{Number, Nothing} = nothing,
+        maxiters::Union{Number, Nothing} = nothing,
+        save_best::Bool = true, progress::Bool = false, kwargs...)
+    return OptimizationCache(prob, opt; callback, epochs, maxiters,
+        save_best, progress, kwargs...)
 end
 
 function SciMLBase.__solve(cache::OptimizationCache{
@@ -50,20 +52,26 @@ function SciMLBase.__solve(cache::OptimizationCache{
         dataiterate = false
     end
 
-    epochs = if cache.solver_args.epochs === nothing
-        if cache.solver_args.maxiters === nothing
-            throw(ArgumentError("The number of iterations must be specified with either the epochs or maxiters kwarg. Where maxiters = epochs*length(data)."))
+    epochs, maxiters = if isnothing(cache.solver_args.maxiters) &&
+                          isnothing(cache.solver_args.epochs)
+        throw(ArgumentError("The number of iterations must be specified with either the epochs or maxiters kwarg. Where maxiters = epochs * length(data)."))
+    elseif !isnothing(cache.solver_args.maxiters) &&
+           !isnothing(cache.solver_args.epochs)
+        if cache.solver_args.maxiters == cache.solver_args.epochs * length(data)
+            cache.solver_args.epochs, cache.solver_args.maxiters
         else
-            cache.solver_args.maxiters / length(data)
+            throw(ArgumentError("The number of iterations must be specified with either the epochs or maxiters kwarg. Where maxiters = epochs * length(data)."))
         end
-    else
-        cache.solver_args.epochs
+    elseif isnothing(cache.solver_args.maxiters)
+        cache.solver_args.epochs, cache.solver_args.epochs * length(data)
+    elseif isnothing(cache.solver_args.epochs)
+        cache.solver_args.maxiters / length(data), cache.solver_args.maxiters
     end
-
     epochs = Optimization._check_and_convert_maxiters(epochs)
-    if epochs === nothing
-        throw(ArgumentError("The number of iterations must be specified with either the epochs or maxiters kwarg. Where maxiters = epochs*length(data)."))
-    end
+    maxiters = Optimization._check_and_convert_maxiters(maxiters)
+
+    # At this point, both of them should be fine; but, let's assert it.
+    @assert (isnothing(epochs)||isnothing(maxiters) || (maxiters != epochs * length(data))) "The number of iterations must be specified with either the epochs or maxiters kwarg. Where maxiters = epochs * length(data)."
 
     opt = cache.opt
     θ = copy(cache.u0)

lib/OptimizationOptimisers/test/runtests.jl

@@ -32,6 +32,19 @@ using Lux, MLUtils, Random, ComponentArrays, Printf, MLDataDevices
     @test sol.stats.fevals == 1000
     @test sol.stats.gevals == 1000
 
+    @testset "epochs & maxiters" begin
+        optprob = SciMLBase.OptimizationFunction(
+            (u, data) -> sum(u) + sum(data), Optimization.AutoZygote())
+        prob = SciMLBase.OptimizationProblem(optprob, ones(2), ones(2))
+        @test_throws ArgumentError solve(prob, Optimisers.Adam())
+        @test_throws ArgumentError solve(
+            prob, Optimisers.Adam(), epochs = 2, maxiters = 2)
+        @test solve(prob, Optimisers.Adam(), epochs = 2)
+        @test solve(prob, Optimisers.Adam(), maxiters = 2)
+        @test solve(prob, Optimisers.Adam(), epochs = 2, maxiters = 4)
+        @test_throws AssertionError solve(prob, Optimisers.Adam(), maxiters = 3)
+    end
+
     @testset "cache" begin
         objective(x, p) = (p[1] - x[1])^2
         x0 = zeros(1)