Add comprehensive docstrings for ODE algorithms

- Added detailed docstrings for CompositeAlgorithm and AutoSwitch in OrdinaryDiffEqCore
- Added docstrings for all Rosenbrock methods in OrdinaryDiffEqRosenbrock
- Included parameter descriptions, usage guidance, and method characteristics
- Enhanced documentation for algorithm switching strategies and stiffness detection

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ChrisRackauckas

lib/OrdinaryDiffEqCore/src/algorithms.jl

@@ -91,6 +91,19 @@ end
 
 #########################################
 
+"""
+    CompositeAlgorithm(algs, choice_function)
+
+A composite algorithm that chooses between multiple ODE solvers based on a user-defined choice function.
+This allows for adaptive algorithm switching based on problem characteristics or performance metrics.
+
+# Arguments
+- `algs`: Tuple or array of ODE algorithms to choose from
+- `choice_function`: Function that determines which algorithm to use at each step
+
+The choice function receives the integrator and should return an index indicating which algorithm to use.
+This enables sophisticated algorithm switching strategies based on solution behavior, step size, or other criteria.
+"""
 struct CompositeAlgorithm{CS, T, F} <: OrdinaryDiffEqCompositeAlgorithm
     algs::T
     choice_function::F
@@ -149,6 +162,28 @@ mutable struct AutoSwitchCache{nAlg, sAlg, tolType, T}
     end
 end
 
+"""
+    AutoSwitch(nonstiffalg, stiffalg; kwargs...)
+
+An automatic algorithm switching method that dynamically chooses between a nonstiff and stiff solver
+based on the problem's stiffness detection. This provides robust performance across a wide range of problems
+without requiring the user to know the problem's stiffness characteristics a priori.
+
+# Arguments
+- `nonstiffalg`: Algorithm to use for nonstiff regions (default: Tsit5())
+- `stiffalg`: Algorithm to use for stiff regions (default: Rodas5P())
+
+# Keywords
+- `maxstiffstep`: Maximum number of consecutive steps before switching from nonstiff to stiff (default: 10)
+- `maxnonstiffstep`: Maximum number of consecutive steps before switching from stiff to nonstiff (default: 3)
+- `nonstifftol`: Tolerance for detecting nonstiff behavior (default: 3//4)
+- `stifftol`: Tolerance for detecting stiff behavior (default: 9//10)
+- `dtfac`: Factor for step size adjustment during switches (default: 2.0)
+- `stiffalgfirst`: Whether to start with the stiff algorithm (default: false)
+- `switch_max`: Maximum number of algorithm switches allowed (default: 10)
+
+The switching decision is based on step size rejections and stability estimates.
+"""
 struct AutoSwitch{nAlg, sAlg, tolType, T}
     nonstiffalg::nAlg
     stiffalg::sAlg

lib/OrdinaryDiffEqRosenbrock/src/algorithms.jl

@@ -138,6 +138,46 @@ Rosenbrock23
     "Rodas5P", with_step_limiter = true)
 Rodas5P
 
+@doc rosenbrock_docstring(
+    "A 3/2-order L-stable Rosenbrock-W method optimized for stiff problems. Good balance of accuracy and computational efficiency.",
+    "Rosenbrock32", with_step_limiter = true)
+Rosenbrock32
+
+@doc rosenbrock_docstring(
+    "A 3rd-order accurate L-stable Rosenbrock method designed for parabolic problems. Particularly effective for reaction-diffusion equations.",
+    "ROS3P", with_step_limiter = true)
+ROS3P
+
+@doc rosenbrock_docstring(
+    "A 3rd-order accurate L-stable Rosenbrock method from Hairer and Wanner. Good general-purpose stiff ODE solver with moderate computational cost.",
+    "Rodas3", with_step_limiter = true)
+Rodas3
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method. Well-suited for moderately stiff problems with good efficiency.",
+    "Rodas4", with_step_limiter = true)
+Rodas4
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with improved error estimation. Enhanced version of Rodas4 for better step size control.",
+    "Rodas42", with_step_limiter = true)
+Rodas42
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method designed for differential-algebraic equations (DAEs). Optimized for index-1 DAE problems.",
+    "Rodas4P", with_step_limiter = true)
+Rodas4P
+
+@doc rosenbrock_docstring(
+    "An improved 4th-order accurate L-stable Rosenbrock method for DAEs with enhanced stability properties.",
+    "Rodas4P2", with_step_limiter = true)
+Rodas4P2
+
+@doc rosenbrock_docstring(
+    "A 5th-order accurate L-stable Rosenbrock method for differential-algebraic problems. Higher accuracy but increased computational cost.",
+    "Rodas5", with_step_limiter = true)
+Rodas5
+
 struct GeneralRosenbrock{CS, AD, F, ST, CJ, TabType} <:
        OrdinaryDiffEqRosenbrockAdaptiveAlgorithm{CS, AD, Val{:forward}, ST, CJ}
     tableau::TabType
@@ -225,3 +265,68 @@ for Alg in [
         end
     end
 end
+
+@doc rosenbrock_docstring(
+    "A 2nd-order accurate L-stable Rosenbrock method. Simple and robust for moderately stiff problems with lower accuracy requirements.",
+    "ROS2")
+ROS2
+
+@doc rosenbrock_docstring(
+    "A 2nd-order accurate L-stable Rosenbrock method optimized for the Prothero-Robinson test problem. Good for oscillatory stiff problems.",
+    "ROS2PR")
+ROS2PR
+
+@doc rosenbrock_docstring(
+    "A 2nd-order accurate L-stable Rosenbrock method with enhanced stability properties. Variant of ROS2 with improved behavior.",
+    "ROS2S")
+ROS2S
+
+@doc rosenbrock_docstring(
+    "A 3rd-order accurate L-stable Rosenbrock method from Hairer and Wanner. Well-established method for general stiff ODEs.",
+    "ROS3")
+ROS3
+
+@doc rosenbrock_docstring(
+    "A 3rd-order accurate L-stable Rosenbrock method optimized for the Prothero-Robinson test problem. Good for stiff oscillatory systems.",
+    "ROS3PR")
+ROS3PR
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with optimized stability function. Enhanced performance for certain stiff problem classes.",
+    "Scholz4_7")
+Scholz4_7
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with improved embedded error estimator. Part of the ROS34PW family of methods.",
+    "ROS34PW1a")
+ROS34PW1a
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with alternative embedded error estimator. Variant in the ROS34PW family.",
+    "ROS34PW1b")
+ROS34PW1b
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with enhanced embedded error estimation. Second variant in the ROS34PW family.",
+    "ROS34PW2")
+ROS34PW2
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method with optimized embedded error estimator. Third variant in the ROS34PW family.",
+    "ROS34PW3")
+ROS34PW3
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method designed for improved traditional Rosenbrock-Wanner methods for stiff ODEs and DAEs.",
+    "ROS34PRw")
+ROS34PRw
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method implemented by Shampine. Classical implementation of a 4th-order Rosenbrock method.",
+    "RosShamp4")
+RosShamp4
+
+@doc rosenbrock_docstring(
+    "A 4th-order accurate L-stable Rosenbrock method optimized for L-stability. Enhanced stability properties from Hairer and Wanner.",
+    "Ros4LStab")
+Ros4LStab