Make max_stepsize more user friendly

Changelog.md

@@ -5,6 +5,14 @@ All notable Changes to the Julia package `Manopt.jl` will be documented in this
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.5.3] – October 18, 2024
+
+### Changed
+
+* stabilize `max_Stepzise` to also work when `injectivity_radius` dos not exist.
+  It however would warn new users, that activate tutorial mode.
+* Start a `ManoptTestSuite` subpackage to store dummy types and common test helpers in.
+
 ## [0.5.2] – October 5, 2024
 
 ### Added

Project.toml

@@ -53,7 +53,7 @@ LinearAlgebra = "1.6"
 ManifoldDiff = "0.3.8"
 Manifolds = "0.9.11, 0.10"
 ManifoldsBase = "0.15.10"
-ManoptExamples = "0.1.8"
+ManoptExamples = "0.1.10"
 Markdown = "1.6"
 Plots = "1.30"
 Preferences = "1.4"

ext/ManoptManifoldsExt/manifold_functions.jl

@@ -9,7 +9,9 @@ on a tangent bundle might be.
 function max_stepsize(M::TangentBundle, p)
     return max_stepsize(M.manifold, p[M, :point])
 end
-
+function max_stepsize(M::TangentBundle)
+    return max_stepsize(M.manifold)
+end
 """
     max_stepsize(M::FixedRankMatrices, p)
 

src/documentation_glossary.jl

@@ -138,6 +138,11 @@ define!(
     :AbstractManifold,
     "[`AbstractManifold`](@extref `ManifoldsBase.AbstractManifold`)",
 )
+define!(
+    :Link,
+    :injectivity_radius,
+    "[`injectivity_radius`](@extref `ManifoldsBase.injectivity_radius-Tuple{AbstractManifold}`)",
+)
 define!(
     :Link,
     :manifold_dimension,

src/plans/stepsize.jl

@@ -35,13 +35,28 @@ default_stepsize(M::AbstractManifold, sT::Type{<:AbstractManoptSolverState})
 Get the maximum stepsize (at point `p`) on manifold `M`. It should be used to limit the
 distance an algorithm is trying to move in a single step.
 
-By default, this returns [`injectivity_radius`](@extref `ManifoldsBase.injectivity_radius-Tuple{AbstractManifold}`)`(M)`.
+By default, this returns $(_link(:injectivity_radius))`(M)`, if this exists.
+If this is not available on the the method returns `Inf`.
 """
 function max_stepsize(M::AbstractManifold, p)
-    return max_stepsize(M)
+    s = try
+        injectivity_radius(M, p)
+    catch
+        is_tutorial_mode() &&
+            @warn "`max_stepsize was called, but there seems to not be an `injectivity_raidus` available on $M."
+        Inf
+    end
+    return s
 end
 function max_stepsize(M::AbstractManifold)
-    return injectivity_radius(M)
+    s = try
+        injectivity_radius(M)
+    catch
+        is_tutorial_mode() &&
+            @warn "`max_stepsize was called, but there seems to not be an `injectivity_raidus` available on $M."
+        Inf
+    end
+    return s
 end
 
 """
@@ -305,11 +320,11 @@ $(_var(:Keyword, :retraction_method))
 * `contraction_factor=0.95`
 * `sufficient_decrease=0.1`
 * `last_stepsize=initialstepsize`
-* `initial_guess=[`armijo_initial_guess`](@ref) – (p,s,i,l) -> l`
-* `stop_when_stepsize_less=0.0`
-* `stop_when_stepsize_exceeds`
-* `stop_increasing_at_step=100`
-* `stop_decreasing_at_step=1000`
+* `initial_guess=`[`armijo_initial_guess`](@ref)` – (p,s,i,l) -> l`
+* `stop_when_stepsize_less=0.0`: stop when the stepsize decreased below this version.
+* `stop_when_stepsize_exceeds=[`max_step`](@ref)`(M)`: provide an absolute maximal step size.
+* `stop_increasing_at_step=100`: for the initial increase test, stop after these many steps
+* `stop_decreasing_at_step=1000`: in the backtrack, stop after these many steps
 """
 mutable struct ArmijoLinesearchStepsize{TRM<:AbstractRetractionMethod,P,I,F,IGF,DF,IF} <:
                Linesearch

test/ManoptTestSuite.jl/ManoptTestSuite.jl

@@ -0,0 +1,11 @@
+"""
+    ManoptTestSuite.jl
+
+A small module to provide common dummy types and defaults for testing.
+"""
+module ManoptTestSuite
+using Manopt, Test, ManifoldsBase
+
+struct DummyManifold <: AbstractManifold{ManifoldsBase.ℝ} end
+
+end

test/helpers/test_manifold_extra_functions.jl

@@ -72,7 +72,9 @@ Random.seed!(42)
         p = [0.0, 1.0, 0.0]
         X = [0.0, 0.0, 0.0]
 
+        @test Manopt.max_stepsize(M) == π
         @test Manopt.max_stepsize(M, p) == π
+        @test Manopt.max_stepsize(TM) == π
         @test Manopt.max_stepsize(TM, ArrayPartition(p, X)) == π
         @test Manopt.max_stepsize(
             TTM, ArrayPartition(ArrayPartition(p, X), ArrayPartition(X, X))

test/plans/test_stepsize.jl

@@ -1,5 +1,9 @@
 using ManifoldsBase, Manopt, Manifolds, Test
 
+s = joinpath(@__DIR__, "..", "ManoptTestSuite.jl")
+!(s in LOAD_PATH) && (push!(LOAD_PATH, s))
+using ManoptTestSuite
+
 @testset "Stepsize" begin
     M = ManifoldsBase.DefaultManifold(2)
     @test Manopt.get_message(Manopt.ConstantStepsize(M, 1.0)) == ""
@@ -124,4 +128,9 @@ using ManifoldsBase, Manopt, Manifolds, Test
             "Polyak()\nA stepsize with keyword parameters\n   * initial_cost_estimate = 0.0\n"
         @test ps(dmp, sgs, 1) == (f(M, p) - 0 + 1) / (norm(M, p, X)^2)
     end
+    @testset "max_stepsize fallbacks" begin
+        M = ManoptTestSuite.DummyManifold()
+        @test isinf(Manopt.max_stepsize(M))
+        @test isinf(Manopt.max_stepsize(M, :NoPoint))
+    end
 end

test/solvers/test_cma_es.jl

@@ -107,9 +107,9 @@ flat_example(::AbstractManifold, p) = 0.0
             flat_example,
             [10.0, 10.0];
             σ=10.0,
-            stopping_criterion=StopAfterIteration(500) |
+            stopping_criterion=StopAfterIteration(1000) |
                                StopWhenPopulationStronglyConcentrated(1e-5),
-            rng=MersenneTwister(123),
+            rng=MersenneTwister(12),
             return_state=true,
         )
         flat_sc = only(get_active_stopping_criteria(o_flat.stop))