From 816df128b28820c190308f109cbd1f3e62fe54fd Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Mon, 15 Dec 2025 12:58:12 +0100
Subject: [PATCH 1/8] Added absolute tolerance to common interface

---
 pypesto/optimize/optimizer.py                 | 148 ++++++++++++++++++
 .../test_optimizer_common_interface.py        |  88 +++++++++++
 2 files changed, 236 insertions(+)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index 45fbdc2b9..8dc07ac85 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -405,6 +405,36 @@ def set_maxeval(self, evaluations: int) -> None:
             f"Check supports_maxeval() before calling set_maxeval()."
         )
 
+    def supports_tol(self) -> bool:
+        """
+        Check whether optimizer supports absolute tolerance.
+
+        Returns
+        -------
+        True if optimizer supports setting an absolute tolerance,
+        False otherwise.
+        """
+        return False
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+
+        Raises
+        ------
+        NotImplementedError
+            If the optimizer does not support absolute tolerance.
+        """
+        raise NotImplementedError(
+            f"{self.__class__.__name__} does not support absolute tolerance. "
+            f"Check supports_tol() before calling set_tol()."
+        )
+
 
 class ScipyOptimizer(Optimizer):
     """
@@ -662,6 +692,21 @@ def set_maxiter(self, iterations: int) -> None:
         else:
             self.options["maxiter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        self.tol = tol
+
 
 class IpoptOptimizer(Optimizer):
     """Use Ipopt (https://pypi.org/project/cyipopt/) for optimization."""
@@ -781,6 +826,23 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["max_iter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        if self.options is None:
+            self.options = {}
+        self.options["tol"] = tol
+
 
 class DlibOptimizer(Optimizer):
     """Use the Dlib toolbox for optimization."""
@@ -949,6 +1011,23 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        if self.options is None:
+            self.options = {}
+        self.options["minfunc"] = tol
+
 
 class CmaOptimizer(Optimizer):
     """
@@ -1062,6 +1141,23 @@ def set_maxeval(self, evaluations: int) -> None:
             self.options = {}
         self.options["maxfevals"] = evaluations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        if self.options is None:
+            self.options = {}
+        self.options["tolfun"] = tol
+
 
 class CmaesOptimizer(CmaOptimizer):
     """Deprecated, use CmaOptimizer instead."""
@@ -1159,6 +1255,23 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        if self.options is None:
+            self.options = {}
+        self.options["atol"] = tol
+
 
 class PyswarmsOptimizer(Optimizer):
     """
@@ -1572,6 +1685,21 @@ def set_maxeval(self, evaluations: int) -> None:
         """
         self.options["maxeval"] = evaluations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        self.options["ftol_abs"] = tol
+
 
 class FidesOptimizer(Optimizer):
     """
@@ -1796,3 +1924,23 @@ def set_maxiter(self, iterations: int) -> None:
             self.options[FidesOptions.MAXITER] = iterations
         except ImportError:
             raise OptimizerImportError("fides") from None
+
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return True
+
+    def set_tol(self, tol: float) -> None:
+        """
+        Set the absolute tolerance for optimization.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance for termination.
+        """
+        try:
+            from fides.constants import Options as FidesOptions
+
+            self.options[FidesOptions.FTOL] = tol
+        except ImportError:
+            raise OptimizerImportError("fides") from None
diff --git a/test/optimize/test_optimizer_common_interface.py b/test/optimize/test_optimizer_common_interface.py
index 63595cb91..9f534d173 100644
--- a/test/optimize/test_optimizer_common_interface.py
+++ b/test/optimize/test_optimizer_common_interface.py
@@ -200,3 +200,91 @@ def test_ipopt_optimizer_no_support(self):
 
         with pytest.raises(NotImplementedError):
             optimizer.set_maxeval(100)
+
+
+class TestOptimizerTolInterface:
+    """Test the unified tolerance interface for optimizers."""
+
+    def test_scipy_optimizer_support(self):
+        """Test ScipyOptimizer tolerance support."""
+        optimizer = optimize.ScipyOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-6)
+        assert optimizer.tol == 1e-6
+
+        # Test updating existing value
+        optimizer.set_tol(1e-8)
+        assert optimizer.tol == 1e-8
+
+    def test_ipopt_optimizer_support(self):
+        """Test IpoptOptimizer tolerance support."""
+        optimizer = optimize.IpoptOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-7)
+        assert optimizer.options["tol"] == 1e-7
+
+    def test_nlopt_optimizer_support(self):
+        """Test NLoptOptimizer tolerance support."""
+        optimizer = optimize.NLoptOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-5)
+        assert optimizer.options["ftol_abs"] == 1e-5
+
+    def test_fides_optimizer_support(self):
+        """Test FidesOptimizer tolerance support."""
+        optimizer = optimize.FidesOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-6)
+
+        from fides.constants import Options as FidesOptions
+
+        assert FidesOptions.FTOL in optimizer.options
+        assert optimizer.options[FidesOptions.FTOL] == 1e-6
+
+        # Test updating existing value
+        optimizer.set_tol(1e-9)
+        assert optimizer.options[FidesOptions.FTOL] == 1e-9
+
+    def test_cma_optimizer_support(self):
+        """Test CmaOptimizer tolerance support."""
+        optimizer = optimize.CmaOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-4)
+        assert optimizer.options["tolfun"] == 1e-4
+
+    def test_scipy_de_optimizer_support(self):
+        """Test ScipyDifferentialEvolutionOptimizer tolerance support."""
+        optimizer = optimize.ScipyDifferentialEvolutionOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-5)
+        assert optimizer.options["atol"] == 1e-5
+
+    def test_pyswarm_optimizer_support(self):
+        """Test PyswarmOptimizer tolerance support."""
+        optimizer = optimize.PyswarmOptimizer()
+        assert optimizer.supports_tol() is True
+
+        optimizer.set_tol(1e-7)
+        assert optimizer.options["minfunc"] == 1e-7
+
+    def test_dlib_optimizer_no_support(self):
+        """Test that DlibOptimizer does not support tolerance."""
+        optimizer = optimize.DlibOptimizer()
+        assert optimizer.supports_tol() is False
+
+        with pytest.raises(NotImplementedError):
+            optimizer.set_tol(1e-6)
+
+    def test_pyswarms_optimizer_no_support(self):
+        """Test that PyswarmsOptimizer does not support tolerance."""
+        optimizer = optimize.PyswarmsOptimizer()
+        assert optimizer.supports_tol() is False
+
+        with pytest.raises(NotImplementedError):
+            optimizer.set_tol(1e-6)

From cef62b6600994ab27dcff8e7fa5529e5bfa44d18 Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Mon, 15 Dec 2025 13:29:12 +0100
Subject: [PATCH 2/8] Restructured and also test for errors

---
 pypesto/optimize/optimizer.py                 | 85 ++++++++++---------
 .../test_optimizer_common_interface.py        | 22 ++++-
 2 files changed, 62 insertions(+), 45 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index 8dc07ac85..bda5886b8 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -414,7 +414,7 @@ def supports_tol(self) -> bool:
         True if optimizer supports setting an absolute tolerance,
         False otherwise.
         """
-        return False
+        return True
 
     def set_tol(self, tol: float) -> None:
         """
@@ -435,6 +435,28 @@ def set_tol(self, tol: float) -> None:
             f"Check supports_tol() before calling set_tol()."
         )
 
+    def _set_option_tol(self, tol: float, option_key: str) -> None:
+        """
+        Set tolerance in options dict with validation.
+
+        Parameters
+        ----------
+        tol
+            Absolute tolerance value (must be positive).
+        option_key
+            The key to use in the options dictionary.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
+        """
+        if tol <= 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if self.options is None:
+            self.options = {}
+        self.options[option_key] = tol
+
 
 class ScipyOptimizer(Optimizer):
     """
@@ -692,10 +714,6 @@ def set_maxiter(self, iterations: int) -> None:
         else:
             self.options["maxiter"] = iterations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -704,7 +722,14 @@ def set_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
+        if tol <= 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
         self.tol = tol
 
 
@@ -826,10 +851,6 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["max_iter"] = iterations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -839,9 +860,7 @@ def set_tol(self, tol: float) -> None:
         tol
             Absolute tolerance for termination.
         """
-        if self.options is None:
-            self.options = {}
-        self.options["tol"] = tol
+        self._set_option_tol(tol, "tol")
 
 
 class DlibOptimizer(Optimizer):
@@ -936,6 +955,10 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return False
+
 
 class PyswarmOptimizer(Optimizer):
     """Global optimization using pyswarm."""
@@ -1011,10 +1034,6 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -1024,9 +1043,7 @@ def set_tol(self, tol: float) -> None:
         tol
             Absolute tolerance for termination.
         """
-        if self.options is None:
-            self.options = {}
-        self.options["minfunc"] = tol
+        self._set_option_tol(tol, "minfunc")
 
 
 class CmaOptimizer(Optimizer):
@@ -1141,10 +1158,6 @@ def set_maxeval(self, evaluations: int) -> None:
             self.options = {}
         self.options["maxfevals"] = evaluations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -1154,9 +1167,7 @@ def set_tol(self, tol: float) -> None:
         tol
             Absolute tolerance for termination.
         """
-        if self.options is None:
-            self.options = {}
-        self.options["tolfun"] = tol
+        self._set_option_tol(tol, "tolfun")
 
 
 class CmaesOptimizer(CmaOptimizer):
@@ -1255,10 +1266,6 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -1268,9 +1275,7 @@ def set_tol(self, tol: float) -> None:
         tol
             Absolute tolerance for termination.
         """
-        if self.options is None:
-            self.options = {}
-        self.options["atol"] = tol
+        self._set_option_tol(tol, "atol")
 
 
 class PyswarmsOptimizer(Optimizer):
@@ -1413,6 +1418,10 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
+    def supports_tol(self) -> bool:
+        """Check whether optimizer supports absolute tolerance."""
+        return False
+
 
 class NLoptOptimizer(Optimizer):
     """
@@ -1685,10 +1694,6 @@ def set_maxeval(self, evaluations: int) -> None:
         """
         self.options["maxeval"] = evaluations
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -1925,10 +1930,6 @@ def set_maxiter(self, iterations: int) -> None:
         except ImportError:
             raise OptimizerImportError("fides") from None
 
-    def supports_tol(self) -> bool:
-        """Check whether optimizer supports absolute tolerance."""
-        return True
-
     def set_tol(self, tol: float) -> None:
         """
         Set the absolute tolerance for optimization.
@@ -1941,6 +1942,6 @@ def set_tol(self, tol: float) -> None:
         try:
             from fides.constants import Options as FidesOptions
 
-            self.options[FidesOptions.FTOL] = tol
+            self.options[FidesOptions.FATOL] = tol
         except ImportError:
             raise OptimizerImportError("fides") from None
diff --git a/test/optimize/test_optimizer_common_interface.py b/test/optimize/test_optimizer_common_interface.py
index 9f534d173..beaf22990 100644
--- a/test/optimize/test_optimizer_common_interface.py
+++ b/test/optimize/test_optimizer_common_interface.py
@@ -242,12 +242,12 @@ def test_fides_optimizer_support(self):
 
         from fides.constants import Options as FidesOptions
 
-        assert FidesOptions.FTOL in optimizer.options
-        assert optimizer.options[FidesOptions.FTOL] == 1e-6
+        assert FidesOptions.FATOL in optimizer.options
+        assert optimizer.options[FidesOptions.FATOL] == 1e-6
 
         # Test updating existing value
         optimizer.set_tol(1e-9)
-        assert optimizer.options[FidesOptions.FTOL] == 1e-9
+        assert optimizer.options[FidesOptions.FATOL] == 1e-9
 
     def test_cma_optimizer_support(self):
         """Test CmaOptimizer tolerance support."""
@@ -288,3 +288,19 @@ def test_pyswarms_optimizer_no_support(self):
 
         with pytest.raises(NotImplementedError):
             optimizer.set_tol(1e-6)
+
+    def test_tolerance_validation(self):
+        """Test that invalid tolerance values are rejected."""
+        optimizer = optimize.ScipyOptimizer()
+
+        # Test that positive values work
+        optimizer.set_tol(1e-6)
+        assert optimizer.tol == 1e-6
+
+    def test_tolerance_validation_options_based(self):
+        """Test tolerance validation for options-based optimizers."""
+        optimizer = optimize.IpoptOptimizer()
+
+        # Test that positive values work
+        optimizer.set_tol(1e-7)
+        assert optimizer.options["tol"] == 1e-7

From 649cb244b31a67017d06684ceae45cff6e49f5ce Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Tue, 16 Dec 2025 15:44:10 +0100
Subject: [PATCH 3/8] always use _set_option_tol wherever possible

---
 pypesto/optimize/optimizer.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index bda5886b8..7a3448d11 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -451,7 +451,7 @@ def _set_option_tol(self, tol: float, option_key: str) -> None:
         ValueError
             If tolerance is not positive.
         """
-        if tol <= 0:
+        if tol < 0:
             raise ValueError(f"Tolerance must be positive, got {tol}")
         if self.options is None:
             self.options = {}
@@ -1703,7 +1703,7 @@ def set_tol(self, tol: float) -> None:
         tol
             Absolute tolerance for termination.
         """
-        self.options["ftol_abs"] = tol
+        self._set_option_tol(tol, "ftol_abs")
 
 
 class FidesOptimizer(Optimizer):
@@ -1942,6 +1942,6 @@ def set_tol(self, tol: float) -> None:
         try:
             from fides.constants import Options as FidesOptions
 
-            self.options[FidesOptions.FATOL] = tol
+            self._set_option_tol(tol, FidesOptions.FATOL)
         except ImportError:
             raise OptimizerImportError("fides") from None

From d7e86fc27282c082083a8eb39e876b9a85141080 Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Tue, 27 Jan 2026 08:55:05 +0100
Subject: [PATCH 4/8] abs_tol

---
 pypesto/optimize/optimizer.py                 | 44 +++++++++++--------
 .../test_optimizer_common_interface.py        | 16 +++++++
 2 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index 451f746eb..79e24796c 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -413,34 +413,34 @@ def set_maxeval(self, evaluations: int) -> None:
             f"Check supports_maxeval() before calling set_maxeval()."
         )
 
-    def supports_tol(self) -> bool:
+    def supports_f_abs_tol(self) -> bool:
         """
-        Check whether optimizer supports absolute tolerance.
+        Check whether optimizer supports absolute function value tolerance.
 
         Returns
         -------
-        True if optimizer supports setting an absolute tolerance,
-        False otherwise.
+        True if optimizer supports setting an absolute tolerance on the
+        objective function value, False otherwise.
         """
         return True
 
-    def set_tol(self, tol: float) -> None:
+    def set_f_abs_tol(self, tol: float) -> None:
         """
-        Set the absolute tolerance for optimization.
+        Set the absolute tolerance on function value for optimization.
 
         Parameters
         ----------
         tol
-            Absolute tolerance for termination.
+            Absolute tolerance on objective function value for termination.
 
         Raises
         ------
         NotImplementedError
-            If the optimizer does not support absolute tolerance.
+            If the optimizer does not support absolute function tolerance.
         """
         raise NotImplementedError(
-            f"{self.__class__.__name__} does not support absolute tolerance. "
-            f"Check supports_tol() before calling set_tol()."
+            f"{self.__class__.__name__} does not support absolute function tolerance. "
+            f"Check supports_f_abs_tol() before calling set_f_abs_tol()."
         )
 
     def _set_option_tol(self, tol: float, option_key: str) -> None:
@@ -722,22 +722,22 @@ def set_maxiter(self, iterations: int) -> None:
         else:
             self.options["maxiter"] = iterations
 
-    def set_tol(self, tol: float) -> None:
+    def set_f_abs_tol(self, tol: float) -> None:
         """
-        Set the absolute tolerance for optimization.
+        Set the absolute tolerance on function value for optimization.
 
         Parameters
         ----------
         tol
-            Absolute tolerance for termination.
+            Absolute tolerance on objective function value for termination.
 
         Raises
         ------
         ValueError
-            If tolerance is not positive.
+            If tolerance is negative.
         """
-        if tol <= 0:
-            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if tol < 0:
+            raise ValueError(f"Tolerance must be non-negative, got {tol}")
         self.tol = tol
 
 
@@ -859,14 +859,20 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["max_iter"] = iterations
 
-    def set_tol(self, tol: float) -> None:
+    def supports_f_abs_tol(self) -> bool:
+        """Check whether optimizer supports absolute function tolerance."""
+        return False
+
+    def set_f_rel_tol(self, tol: float) -> None:
         """
-        Set the absolute tolerance for optimization.
+        Set the relative tolerance on function value for optimization.
+
+        Ipopt uses relative convergence tolerance, not absolute.
 
         Parameters
         ----------
         tol
-            Absolute tolerance for termination.
+            Relative tolerance on objective function value for termination.
         """
         self._set_option_tol(tol, "tol")
 
diff --git a/test/optimize/test_optimizer_common_interface.py b/test/optimize/test_optimizer_common_interface.py
index beaf22990..136000d91 100644
--- a/test/optimize/test_optimizer_common_interface.py
+++ b/test/optimize/test_optimizer_common_interface.py
@@ -297,6 +297,14 @@ def test_tolerance_validation(self):
         optimizer.set_tol(1e-6)
         assert optimizer.tol == 1e-6
 
+        # Test that zero is allowed (optimize as accurately as possible)
+        optimizer.set_tol(0.0)
+        assert optimizer.tol == 0.0
+
+        # Test that negative values are rejected
+        with pytest.raises(ValueError, match="must be non-negative"):
+            optimizer.set_tol(-1e-6)
+
     def test_tolerance_validation_options_based(self):
         """Test tolerance validation for options-based optimizers."""
         optimizer = optimize.IpoptOptimizer()
@@ -304,3 +312,11 @@ def test_tolerance_validation_options_based(self):
         # Test that positive values work
         optimizer.set_tol(1e-7)
         assert optimizer.options["tol"] == 1e-7
+
+        # Test that zero is allowed
+        optimizer.set_tol(0.0)
+        assert optimizer.options["tol"] == 0.0
+
+        # Test that negative values are rejected
+        with pytest.raises(ValueError, match="must be positive"):
+            optimizer.set_tol(-1e-7)

From cbae8ffbbec4992f0aeb73d74a0a9f4ae973cf3f Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Fri, 27 Feb 2026 15:48:11 +0100
Subject: [PATCH 5/8] adjusted for naming in tests

---
 pypesto/optimize/optimizer.py                 |  2 +-
 .../test_optimizer_common_interface.py        | 66 ++++++-------------
 2 files changed, 22 insertions(+), 46 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index ac0c02b05..cda3d16e2 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -915,7 +915,7 @@ def supports_f_abs_tol(self) -> bool:
         """Check whether optimizer supports absolute function tolerance."""
         return False
 
-    def set_f_rel_tol(self, tol: float) -> None:
+    def set_tol(self, tol: float) -> None:
         """
         Set the convergence tolerance.
 
diff --git a/test/optimize/test_optimizer_common_interface.py b/test/optimize/test_optimizer_common_interface.py
index 8d32123bd..a4b2ce867 100644
--- a/test/optimize/test_optimizer_common_interface.py
+++ b/test/optimize/test_optimizer_common_interface.py
@@ -234,37 +234,29 @@ class TestOptimizerTolInterface:
     def test_scipy_optimizer_support(self):
         """Test ScipyOptimizer tolerance support."""
         optimizer = optimize.ScipyOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-6)
+        optimizer.set_f_abs_tol(1e-6)
         assert optimizer.tol == 1e-6
 
         # Test updating existing value
-        optimizer.set_tol(1e-8)
+        optimizer.set_f_abs_tol(1e-8)
         assert optimizer.tol == 1e-8
 
-    def test_ipopt_optimizer_support(self):
-        """Test IpoptOptimizer tolerance support."""
-        optimizer = optimize.IpoptOptimizer()
-        assert optimizer.supports_tol() is True
-
-        optimizer.set_tol(1e-7)
-        assert optimizer.options["tol"] == 1e-7
-
     def test_nlopt_optimizer_support(self):
         """Test NLoptOptimizer tolerance support."""
         optimizer = optimize.NLoptOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-5)
+        optimizer.set_f_abs_tol(1e-5)
         assert optimizer.options["ftol_abs"] == 1e-5
 
     def test_fides_optimizer_support(self):
         """Test FidesOptimizer tolerance support."""
         optimizer = optimize.FidesOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-6)
+        optimizer.set_f_abs_tol(1e-6)
 
         from fides.constants import Options as FidesOptions
 
@@ -272,77 +264,61 @@ def test_fides_optimizer_support(self):
         assert optimizer.options[FidesOptions.FATOL] == 1e-6
 
         # Test updating existing value
-        optimizer.set_tol(1e-9)
+        optimizer.set_f_abs_tol(1e-9)
         assert optimizer.options[FidesOptions.FATOL] == 1e-9
 
     def test_cma_optimizer_support(self):
         """Test CmaOptimizer tolerance support."""
         optimizer = optimize.CmaOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-4)
+        optimizer.set_f_abs_tol(1e-4)
         assert optimizer.options["tolfun"] == 1e-4
 
     def test_scipy_de_optimizer_support(self):
         """Test ScipyDifferentialEvolutionOptimizer tolerance support."""
         optimizer = optimize.ScipyDifferentialEvolutionOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-5)
+        optimizer.set_f_abs_tol(1e-5)
         assert optimizer.options["atol"] == 1e-5
 
     def test_pyswarm_optimizer_support(self):
         """Test PyswarmOptimizer tolerance support."""
         optimizer = optimize.PyswarmOptimizer()
-        assert optimizer.supports_tol() is True
+        assert optimizer.supports_f_abs_tol() is True
 
-        optimizer.set_tol(1e-7)
+        optimizer.set_f_abs_tol(1e-7)
         assert optimizer.options["minfunc"] == 1e-7
 
     def test_dlib_optimizer_no_support(self):
         """Test that DlibOptimizer does not support tolerance."""
         optimizer = optimize.DlibOptimizer()
-        assert optimizer.supports_tol() is False
+        assert optimizer.supports_f_abs_tol() is False
 
         with pytest.raises(NotImplementedError):
-            optimizer.set_tol(1e-6)
+            optimizer.set_f_abs_tol(1e-6)
 
     def test_pyswarms_optimizer_no_support(self):
         """Test that PyswarmsOptimizer does not support tolerance."""
         optimizer = optimize.PyswarmsOptimizer()
-        assert optimizer.supports_tol() is False
+        assert optimizer.supports_f_abs_tol() is False
 
         with pytest.raises(NotImplementedError):
-            optimizer.set_tol(1e-6)
+            optimizer.set_f_abs_tol(1e-6)
 
     def test_tolerance_validation(self):
         """Test that invalid tolerance values are rejected."""
         optimizer = optimize.ScipyOptimizer()
 
         # Test that positive values work
-        optimizer.set_tol(1e-6)
+        optimizer.set_f_abs_tol(1e-6)
         assert optimizer.tol == 1e-6
 
         # Test that zero is allowed (optimize as accurately as possible)
-        optimizer.set_tol(0.0)
+        optimizer.set_f_abs_tol(0.0)
         assert optimizer.tol == 0.0
 
         # Test that negative values are rejected
         with pytest.raises(ValueError, match="must be non-negative"):
-            optimizer.set_tol(-1e-6)
-
-    def test_tolerance_validation_options_based(self):
-        """Test tolerance validation for options-based optimizers."""
-        optimizer = optimize.IpoptOptimizer()
-
-        # Test that positive values work
-        optimizer.set_tol(1e-7)
-        assert optimizer.options["tol"] == 1e-7
-
-        # Test that zero is allowed
-        optimizer.set_tol(0.0)
-        assert optimizer.options["tol"] == 0.0
-
-        # Test that negative values are rejected
-        with pytest.raises(ValueError, match="must be positive"):
-            optimizer.set_tol(-1e-7)
+            optimizer.set_f_abs_tol(-1e-6)

From 4c7ad9c786f00b15c83548fa7259ccc594209915 Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Wed, 4 Mar 2026 14:58:03 +0100
Subject: [PATCH 6/8] Fixed CmaOptimizer support (by chance deleted) and moved
 test to maxtime testing

---
 pypesto/optimize/optimizer.py                    | 12 ++++++++++--
 test/optimize/test_optimizer_common_interface.py | 14 +++++++++-----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index cda3d16e2..c1c48e73c 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -1051,7 +1051,7 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
-    def supports_tol(self) -> bool:
+    def supports_f_abs_tol(self) -> bool:
         """Check whether optimizer supports absolute tolerance."""
         return False
 
@@ -1220,6 +1220,14 @@ def is_least_squares(self):
         """Check whether optimizer is a least squares optimizer."""
         return False
 
+    def supports_maxtime(self):
+        """Check whether optimizer supports time limits."""
+        return True
+
+    def set_maxtime(self, seconds: float) -> None:
+        """Set the maximum wall time for optimization."""
+        self.options["timeout"] = seconds
+
     def supports_maxiter(self) -> bool:
         """Check whether optimizer supports iteration limits."""
         return True
@@ -1518,7 +1526,7 @@ def set_maxiter(self, iterations: int) -> None:
             self.options = {}
         self.options["maxiter"] = iterations
 
-    def supports_tol(self) -> bool:
+    def supports_f_abs_tol(self) -> bool:
         """Check whether optimizer supports absolute tolerance."""
         return False
 
diff --git a/test/optimize/test_optimizer_common_interface.py b/test/optimize/test_optimizer_common_interface.py
index a4b2ce867..b2d3d4820 100644
--- a/test/optimize/test_optimizer_common_interface.py
+++ b/test/optimize/test_optimizer_common_interface.py
@@ -66,6 +66,15 @@ def test_ess_optimizer_support(self):
         optimizer.set_maxtime(10.0)
         assert optimizer.max_walltime_s == 10.0
 
+    def test_cma_optimizer_support(self):
+        """Test CmaOptimizer iteration limit support."""
+        optimizer = optimize.CmaOptimizer()
+
+        assert optimizer.supports_maxtime() is True
+        optimizer.set_maxtime(1000)
+
+        assert optimizer.options["timeout"] == 1000
+
     def test_scipy_optimizer_support(self):
         """Test ScipyOptimizer time limit support."""
         optimizer = optimize.ScipyOptimizer()
@@ -136,11 +145,6 @@ def test_cma_optimizer_support(self):
         optimizer.set_maxiter(5000)
         assert optimizer.options["maxiter"] == 5000
 
-        assert optimizer.supports_maxtime() is True
-        optimizer.set_maxtime(1000)
-
-        assert optimizer.options["timeout"] == 1000
-
     def test_scipy_de_optimizer_support(self):
         """Test ScipyDifferentialEvolutionOptimizer iteration limit support."""
         optimizer = optimize.ScipyDifferentialEvolutionOptimizer()

From c2f4d73deb5a42c491c9c2460bd203f76ee799b4 Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Tue, 24 Mar 2026 10:26:19 +0100
Subject: [PATCH 7/8] integrated comments

---
 pypesto/optimize/optimizer.py | 83 ++++++++++++++++++-----------------
 1 file changed, 43 insertions(+), 40 deletions(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index c1c48e73c..ff1a4af05 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -443,28 +443,6 @@ def set_f_abs_tol(self, tol: float) -> None:
             f"Check supports_f_abs_tol() before calling set_f_abs_tol()."
         )
 
-    def _set_option_tol(self, tol: float, option_key: str) -> None:
-        """
-        Set tolerance in options dict with validation.
-
-        Parameters
-        ----------
-        tol
-            Absolute tolerance value (must be positive).
-        option_key
-            The key to use in the options dictionary.
-
-        Raises
-        ------
-        ValueError
-            If tolerance is not positive.
-        """
-        if tol < 0:
-            raise ValueError(f"Tolerance must be positive, got {tol}")
-        if self.options is None:
-            self.options = {}
-        self.options[option_key] = tol
-
 
 class ScipyOptimizer(Optimizer):
     """
@@ -892,7 +870,9 @@ def set_maxtime(self, seconds: float) -> None:
             )
         if self.options is None:
             self.options = {}
-        self.options["max_wall_time"] = seconds
+        # We explicitly cast to float, as the IpoptOptimizer requires
+        # the provision of a float for the max_wall_time option.
+        self.options["max_wall_time"] = float(seconds)
 
     def supports_maxiter(self) -> bool:
         """Check whether optimizer supports iteration limits."""
@@ -915,19 +895,6 @@ def supports_f_abs_tol(self) -> bool:
         """Check whether optimizer supports absolute function tolerance."""
         return False
 
-    def set_tol(self, tol: float) -> None:
-        """
-        Set the convergence tolerance.
-
-        See https://coin-or.github.io/Ipopt/OPTIONS.html for more information.
-
-        Parameters
-        ----------
-        tol
-            Tolerance value for termination.
-        """
-        self._set_option_tol(tol, "tol")
-
 
 class DlibOptimizer(Optimizer):
     """Use the Dlib toolbox for optimization."""
@@ -1138,8 +1105,17 @@ def set_f_abs_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
-        self._set_option_tol(tol, "minfunc")
+        if tol < 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if self.options is None:
+            self.options = {}
+        self.options["minfunc"] = tol
 
 
 class CmaOptimizer(Optimizer):
@@ -1382,8 +1358,17 @@ def set_f_abs_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
-        self._set_option_tol(tol, "atol")
+        if tol < 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if self.options is None:
+            self.options = {}
+        self.options["atol"] = tol
 
 
 class PyswarmsOptimizer(Optimizer):
@@ -1810,8 +1795,17 @@ def set_f_abs_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
-        self._set_option_tol(tol, "ftol_abs")
+        if tol < 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if self.options is None:
+            self.options = {}
+        self.options["ftol_abs"] = tol
 
 
 class FidesOptimizer(Optimizer):
@@ -2046,10 +2040,19 @@ def set_f_abs_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
+        if tol < 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
         try:
             from fides.constants import Options as FidesOptions
 
-            self._set_option_tol(tol, FidesOptions.FATOL)
+            if self.options is None:
+                self.options = {}
+            self.options[FidesOptions.FATOL] = tol
         except ImportError:
             raise OptimizerImportError("fides") from None

From be9fd7a0b9a63cab52980e9bb76cfbe800d4e120 Mon Sep 17 00:00:00 2001
From: PaulJonasJost <jost.pauljonas@gmail.com>
Date: Tue, 24 Mar 2026 10:27:56 +0100
Subject: [PATCH 8/8] forgot one instance

---
 pypesto/optimize/optimizer.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/pypesto/optimize/optimizer.py b/pypesto/optimize/optimizer.py
index ff1a4af05..26e712e4a 100644
--- a/pypesto/optimize/optimizer.py
+++ b/pypesto/optimize/optimizer.py
@@ -1246,8 +1246,17 @@ def set_f_abs_tol(self, tol: float) -> None:
         ----------
         tol
             Absolute tolerance for termination.
+
+        Raises
+        ------
+        ValueError
+            If tolerance is not positive.
         """
-        self._set_option_tol(tol, "tolfun")
+        if tol < 0:
+            raise ValueError(f"Tolerance must be positive, got {tol}")
+        if self.options is None:
+            self.options = {}
+        self.options["tolfun"] = tol
 
 
 class CmaesOptimizer(CmaOptimizer):