diff --git a/xdeps/__init__.py b/xdeps/__init__.py
index 231600a..bf04235 100644
--- a/xdeps/__init__.py
+++ b/xdeps/__init__.py
@@ -6,7 +6,7 @@
 from .tasks import Manager
 from . import madxutils
 from .table import Table
-from .optimize import (Optimize, Vary, Target, TargetList, VaryList, Action)
+from .optimize import (Optimize, Vary, Target, TargetList, VaryList, Action, MeritFunctionForMatch)
 from .functions import FunctionPieceWiseLinear
 
 from ._version import __version__
@@ -22,6 +22,7 @@
     "TargetList",
     "VaryList",
     "Action",
+    "MeritFunctionForMatch",
     "FunctionPieceWiseLinear",
     "__version__",
 ]
diff --git a/xdeps/optimize/__init__.py b/xdeps/optimize/__init__.py
index eebd6ca..5729da7 100644
--- a/xdeps/optimize/__init__.py
+++ b/xdeps/optimize/__init__.py
@@ -1,4 +1,4 @@
-from .optimize import (Optimize, Vary, Target, TargetList, VaryList, Action)
+from .optimize import (Optimize, Vary, Target, TargetList, VaryList, Action, MeritFunctionForMatch)
 
 
-__all__ = ['Optimize', 'Vary', 'Target', 'TargetList', 'VaryList', 'Action']
\ No newline at end of file
+__all__ = ['Optimize', 'Vary', 'Target', 'TargetList', 'VaryList', 'Action', 'MeritFunctionForMatch']
\ No newline at end of file
diff --git a/xdeps/optimize/jacobian.py b/xdeps/optimize/jacobian.py
index f9e6636..95e851c 100644
--- a/xdeps/optimize/jacobian.py
+++ b/xdeps/optimize/jacobian.py
@@ -61,7 +61,7 @@ def step(self, n_steps=1, rcond = None, sing_val_cutoff = None, broyden = False)
                     _print("Function tolerance met")
                 break
             # Equation search
-            if broyden and hasattr(self, "_last_jac"):
+            if broyden and hasattr(self, "_last_jac") and self._last_jac is not None:
                 dx = self.x - self._last_jac_x
                 dy = y - self._last_y
                 # Broyden update
diff --git a/xdeps/optimize/optimize.py b/xdeps/optimize/optimize.py
index e8504d6..2342a20 100644
--- a/xdeps/optimize/optimize.py
+++ b/xdeps/optimize/optimize.py
@@ -409,6 +409,7 @@ def get_jacobian(self, x, f0=None):
             x[ii] -= steps[ii]
 
         self._last_jac = jac
+        self._set_x(x)
         return jac
 
     def _clip_to_max_steps(self, x_step):
@@ -1018,12 +1019,12 @@ def step(
 
             this_broyden = False
             if broyden:
-                if broyden == True:
+                if isinstance(broyden, bool):
                     this_broyden = True
                 else:
                     assert isinstance(broyden, int)
                     this_broyden = True
-                    if i_step % broyden == 0:
+                    if i_step % (broyden + 1) == 0:
                         this_broyden = False
 
             self.solver.step(
@@ -1291,7 +1292,6 @@ def target_mismatch(self, ret=False, max_col_width=40, maxwidth=1000):
             print("Target mismatch:             ")
             out.show(max_col_width=max_col_width, maxwidth=maxwidth)
 
-
     def get_knob_values(self, iteration=None):
         """
         Get the knob values at a given iteration.
@@ -1692,6 +1692,10 @@ def check_limits(self, value):
     def _err(self):
         return self.solver.func
 
+    @_err.setter
+    def _err(self, value):
+        self.solver.func = value
+
     @property
     def actions(self):
         return self._err.actions