From 81a120bda50a2c787adf9c5f7e04050fd1b7fbfb Mon Sep 17 00:00:00 2001
From: Akshay Sridhar <asridhar@caltech.edu>
Date: Wed, 17 Aug 2022 09:41:24 -0700
Subject: [PATCH] Add RelativeSolutionTolerance option + up tests, docs 
 modified:   src/RootSolvers.jl 	modified:   test/test_helper.jl       
  modified:   docs/src/API.md

+ Bump minor version -> 0.3.4
	modified:   Project.toml
---
 Project.toml        |  2 +-
 docs/src/API.md     |  1 +
 src/RootSolvers.jl  | 18 +++++++++++++++++-
 test/test_helper.jl |  2 +-
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/Project.toml b/Project.toml
index b82e24b..1226b86 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "RootSolvers"
 uuid = "7181ea78-2dcb-4de3-ab41-2b8ab5a31e74"
 authors = ["CliMA Contributors <clima-software@caltech.edu>"]
-version = "0.3.3"
+version = "0.3.4"
 
 [deps]
 DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
diff --git a/docs/src/API.md b/docs/src/API.md
index 4c1810a..6d8b753 100644
--- a/docs/src/API.md
+++ b/docs/src/API.md
@@ -34,6 +34,7 @@ CompactSolutionResults
 ```@docs
 ResidualTolerance
 SolutionTolerance
+RelativeSolutionTolerance
 ```
 
 ## Internal helper methods
diff --git a/src/RootSolvers.jl b/src/RootSolvers.jl
index b789097..8841a83 100644
--- a/src/RootSolvers.jl
+++ b/src/RootSolvers.jl
@@ -26,7 +26,7 @@ using DocStringExtensions: FIELDS
 export find_zero,
     SecantMethod, RegulaFalsiMethod, NewtonsMethodAD, NewtonsMethod
 export CompactSolution, VerboseSolution
-export AbstractTolerance, ResidualTolerance, SolutionTolerance
+export AbstractTolerance, ResidualTolerance, SolutionTolerance, RelativeSolutionTolerance
 
 import ForwardDiff
 
@@ -199,6 +199,22 @@ Evaluates solution tolerance, based on ``|x2-x1|``
 """
 (tol::SolutionTolerance)(x1, x2, y) = abs(x2 - x1) < tol.tol
 
+"""
+    RelativeSolutionTolerance
+
+A tolerance type based on consecutive iterations of solution ``x`` of the equation ``f(x) = 0``
+"""
+struct RelativeSolutionTolerance{FT} <: AbstractTolerance{FT}
+    tol::FT
+end
+
+"""
+    (tol::RelativeSolutionTolerance)(x1, x2, y)
+
+Evaluates solution tolerance, based on ``|(x2-x1)/x1|``
+"""
+(tol::RelativeSolutionTolerance)(x1, x2, y) = abs((x2 - x1)/x1) < tol.tol
+
 # TODO: CuArrays.jl has trouble with isapprox on 1.1
 # we use simple checks for now, will switch to relative checks later.
 
diff --git a/test/test_helper.jl b/test/test_helper.jl
index c762d45..738ca58 100644
--- a/test/test_helper.jl
+++ b/test/test_helper.jl
@@ -31,7 +31,7 @@ end
 problem_size() = 5
 problem_size(::RootSolvingProblem{S,F,F′,FT,FTA,N}) where {S,F,F′,FT,FTA,N} = N
 float_types() = [Float32, Float64]
-get_tolerances(FT) = [ResidualTolerance{FT}(1e-6), SolutionTolerance{FT}(1e-3), nothing]
+get_tolerances(FT) = [ResidualTolerance{FT}(1e-6), SolutionTolerance{FT}(1e-3), RelativeSolutionTolerance{FT}(sqrt(eps(FT))), nothing]
 
 test_verbose!(::CompactSolution, sol, problem, tol, converged) = nothing
 function test_verbose!(::VerboseSolution, sol, problem, tol, converged)