diff --git a/surfaces/_base_test_function.py b/surfaces/_base_test_function.py
new file mode 100644
index 0000000..7ff4525
--- /dev/null
+++ b/surfaces/_base_test_function.py
@@ -0,0 +1,102 @@
+# Author: Simon Blanke
+# Email: simon.blanke@yahoo.com
+# License: MIT License
+
+
+import time
+import numpy as np
+import pandas as pd
+from functools import reduce
+
+from hyperactive import Hyperactive
+from hyperactive.optimizers import GridSearchOptimizer
+
+from ..machine_learning.data_collector import SurfacesDataCollector
+
+
+class ObjectiveFunction:
+    explanation = """ """
+
+    dimensions = " "
+    formula = r" "
+    global_minimum = r" "
+
+    def __init__(self, metric="score", input_type="dictionary", sleep=0):
+        self.metric = metric
+        self.input_type = input_type
+        self.sleep = sleep
+
+        self.sql_data = SurfacesDataCollector()
+
+    def search_space(self, min=-5, max=5, step=0.1, value_typ="array"):
+        search_space_ = {}
+
+        for dim in range(self.n_dim):
+            dim_str = "x" + str(dim)
+
+            values = np.arange(min, max, step)
+            if value_typ == "list":
+                values = list(values)
+            search_space_[dim_str] = values
+
+        return search_space_
+
+    def collect_data(self, if_exists="append"):
+        para_names = list(self.search_space().keys())
+        search_data_cols = para_names + ["score"]
+        search_data = pd.DataFrame([], columns=search_data_cols)
+        search_data_length = 0
+
+        dim_sizes_list = [len(array) for array in self.search_space().values()]
+        search_space_size = reduce((lambda x, y: x * y), dim_sizes_list)
+
+        while search_data_length < search_space_size:
+            hyper = Hyperactive(verbosity=["progress_bar"])
+            hyper.add_search(
+                self.objective_function_dict,
+                self.search_space(value_typ="list"),
+                initialize={},
+                n_iter=search_space_size,
+                optimizer=GridSearchOptimizer(direction="orthogonal"),
+                memory_warm_start=search_data,
+            )
+            hyper.run()
+
+            search_data = pd.concat(
+                [search_data, hyper.search_data(self.objective_function_dict)],
+                ignore_index=True,
+            )
+
+            search_data = search_data.drop_duplicates(subset=para_names)
+            search_data_length = len(search_data)
+
+        self.sql_data.save(self.__name__, search_data, if_exists)
+
+    def load_search_data(self):
+        try:
+            dataframe = self.sql_data.load(self.__name__)
+        except:
+            print("Path 2 database: ", self.sql_data.path)
+        return dataframe
+
+    def return_metric(self, loss):
+        if self.metric == "score":
+            return -loss
+        elif self.metric == "loss":
+            return loss
+
+    def objective_function_np(self, *args):
+        para = {}
+        for i, arg in enumerate(args):
+            dim_str = "x" + str(i)
+            para[dim_str] = arg
+
+        return self.objective_function_dict(para)
+
+    def __call__(self, *input):
+        time.sleep(self.sleep)
+
+        if self.input_type == "dictionary":
+            return self.objective_function_dict(*input)
+        elif self.input_type == "arrays":
+            return self.objective_function_np(*input)
diff --git a/surfaces/machine_learning/data_collector/__init__.py b/surfaces/data_collector/__init__.py
similarity index 100%
rename from surfaces/machine_learning/data_collector/__init__.py
rename to surfaces/data_collector/__init__.py
diff --git a/surfaces/machine_learning/data_collector/config.py b/surfaces/data_collector/config.py
similarity index 100%
rename from surfaces/machine_learning/data_collector/config.py
rename to surfaces/data_collector/config.py
diff --git a/surfaces/machine_learning/data_collector/surfaces_data_collector.py b/surfaces/data_collector/surfaces_data_collector.py
similarity index 100%
rename from surfaces/machine_learning/data_collector/surfaces_data_collector.py
rename to surfaces/data_collector/surfaces_data_collector.py
diff --git a/surfaces/machine_learning/__init__.py b/surfaces/machine_learning/__init__.py
deleted file mode 100644
index fe38a8a..0000000
--- a/surfaces/machine_learning/__init__.py
+++ /dev/null
@@ -1,9 +0,0 @@
-# Author: Simon Blanke
-# Email: simon.blanke@yahoo.com
-# License: MIT License
-
-from .machine_learning_functions.tabular_classifiers import KNeighborsClassifierFunction
-from .machine_learning_functions.tabular_regressors import (
-    GradientBoostingRegressorFunction,
-    KNeighborsRegressorFunction,
-)
diff --git a/surfaces/machine_learning/machine_learning_functions/__init__.py b/surfaces/machine_learning_functions/__init__.py
similarity index 100%
rename from surfaces/machine_learning/machine_learning_functions/__init__.py
rename to surfaces/machine_learning_functions/__init__.py
diff --git a/surfaces/machine_learning/machine_learning_functions/base_machine_learning_function.py b/surfaces/machine_learning_functions/base_machine_learning_function.py
similarity index 97%
rename from surfaces/machine_learning/machine_learning_functions/base_machine_learning_function.py
rename to surfaces/machine_learning_functions/base_machine_learning_function.py
index c8d6681..c7e8daf 100644
--- a/surfaces/machine_learning/machine_learning_functions/base_machine_learning_function.py
+++ b/surfaces/machine_learning_functions/base_machine_learning_function.py
@@ -1,4 +1,8 @@
-import os
+# Author: Simon Blanke
+# Email: simon.blanke@yahoo.com
+# License: MIT License
+
+
 import time
 
 import numpy as np
diff --git a/surfaces/machine_learning/datasets/__init__.py b/surfaces/machine_learning_functions/datasets/__init__.py
similarity index 100%
rename from surfaces/machine_learning/datasets/__init__.py
rename to surfaces/machine_learning_functions/datasets/__init__.py
diff --git a/surfaces/machine_learning/datasets/tabular_classification.py b/surfaces/machine_learning_functions/datasets/tabular_classification.py
similarity index 100%
rename from surfaces/machine_learning/datasets/tabular_classification.py
rename to surfaces/machine_learning_functions/datasets/tabular_classification.py
diff --git a/surfaces/machine_learning/datasets/tabular_regression.py b/surfaces/machine_learning_functions/datasets/tabular_regression.py
similarity index 100%
rename from surfaces/machine_learning/datasets/tabular_regression.py
rename to surfaces/machine_learning_functions/datasets/tabular_regression.py
diff --git a/surfaces/machine_learning/machine_learning_functions/tabular_classifiers.py b/surfaces/machine_learning_functions/tabular_classifiers.py
similarity index 94%
rename from surfaces/machine_learning/machine_learning_functions/tabular_classifiers.py
rename to surfaces/machine_learning_functions/tabular_classifiers.py
index 17db33c..a891298 100644
--- a/surfaces/machine_learning/machine_learning_functions/tabular_classifiers.py
+++ b/surfaces/machine_learning_functions/tabular_classifiers.py
@@ -4,7 +4,7 @@
 from sklearn.neighbors import KNeighborsClassifier
 
 from sklearn.model_selection import cross_val_score
-from ..datasets import digits_data, wine_data, iris_data
+from .datasets import digits_data, wine_data, iris_data
 
 from .base_machine_learning_function import BaseMachineLearningFunction
 
diff --git a/surfaces/machine_learning/machine_learning_functions/tabular_regressors.py b/surfaces/machine_learning_functions/tabular_regressors.py
similarity index 97%
rename from surfaces/machine_learning/machine_learning_functions/tabular_regressors.py
rename to surfaces/machine_learning_functions/tabular_regressors.py
index 9c96e42..bcd7429 100644
--- a/surfaces/machine_learning/machine_learning_functions/tabular_regressors.py
+++ b/surfaces/machine_learning_functions/tabular_regressors.py
@@ -5,7 +5,7 @@
 from sklearn.ensemble import GradientBoostingRegressor
 
 from sklearn.model_selection import cross_val_score
-from ..datasets import diabetes_data
+from .datasets import diabetes_data
 
 from .base_machine_learning_function import BaseMachineLearningFunction
 
diff --git a/surfaces/test_functions/__init__.py b/surfaces/mathematical_functions/__init__.py
similarity index 100%
rename from surfaces/test_functions/__init__.py
rename to surfaces/mathematical_functions/__init__.py
diff --git a/surfaces/test_functions/_base_objective_function.py b/surfaces/mathematical_functions/_base_objective_function.py
similarity index 95%
rename from surfaces/test_functions/_base_objective_function.py
rename to surfaces/mathematical_functions/_base_objective_function.py
index a2f2b83..1fbf5b6 100644
--- a/surfaces/test_functions/_base_objective_function.py
+++ b/surfaces/mathematical_functions/_base_objective_function.py
@@ -11,10 +11,16 @@
 from hyperactive import Hyperactive
 from hyperactive.optimizers import GridSearchOptimizer
 
-from ..machine_learning.data_collector import SurfacesDataCollector
+from ..data_collector import SurfacesDataCollector
 
 
 class ObjectiveFunction:
+    explanation = """ """
+
+    dimensions = " "
+    formula = r" "
+    global_minimum = r" "
+
     def __init__(self, metric="score", input_type="dictionary", sleep=0):
         self.metric = metric
         self.input_type = input_type
diff --git a/surfaces/test_functions/ackley_function.py b/surfaces/mathematical_functions/ackley_function.py
similarity index 100%
rename from surfaces/test_functions/ackley_function.py
rename to surfaces/mathematical_functions/ackley_function.py
diff --git a/surfaces/test_functions/beale_function.py b/surfaces/mathematical_functions/beale_function.py
similarity index 100%
rename from surfaces/test_functions/beale_function.py
rename to surfaces/mathematical_functions/beale_function.py
diff --git a/surfaces/test_functions/booth_function.py b/surfaces/mathematical_functions/booth_function.py
similarity index 100%
rename from surfaces/test_functions/booth_function.py
rename to surfaces/mathematical_functions/booth_function.py
diff --git a/surfaces/test_functions/bukin_function_n6.py b/surfaces/mathematical_functions/bukin_function_n6.py
similarity index 100%
rename from surfaces/test_functions/bukin_function_n6.py
rename to surfaces/mathematical_functions/bukin_function_n6.py
diff --git a/surfaces/test_functions/cross_in_tray_function.py b/surfaces/mathematical_functions/cross_in_tray_function.py
similarity index 100%
rename from surfaces/test_functions/cross_in_tray_function.py
rename to surfaces/mathematical_functions/cross_in_tray_function.py
diff --git a/surfaces/test_functions/drop_wave_function.py b/surfaces/mathematical_functions/drop_wave_function.py
similarity index 100%
rename from surfaces/test_functions/drop_wave_function.py
rename to surfaces/mathematical_functions/drop_wave_function.py
diff --git a/surfaces/test_functions/easom_function.py b/surfaces/mathematical_functions/easom_function.py
similarity index 100%
rename from surfaces/test_functions/easom_function.py
rename to surfaces/mathematical_functions/easom_function.py
diff --git a/surfaces/test_functions/eggholder_function.py b/surfaces/mathematical_functions/eggholder_function.py
similarity index 100%
rename from surfaces/test_functions/eggholder_function.py
rename to surfaces/mathematical_functions/eggholder_function.py
diff --git a/surfaces/test_functions/goldstein_price_function.py b/surfaces/mathematical_functions/goldstein_price_function.py
similarity index 100%
rename from surfaces/test_functions/goldstein_price_function.py
rename to surfaces/mathematical_functions/goldstein_price_function.py
diff --git a/surfaces/test_functions/gramacy_and_lee_function.py b/surfaces/mathematical_functions/gramacy_and_lee_function.py
similarity index 100%
rename from surfaces/test_functions/gramacy_and_lee_function.py
rename to surfaces/mathematical_functions/gramacy_and_lee_function.py
diff --git a/surfaces/test_functions/griewank_function.py b/surfaces/mathematical_functions/griewank_function.py
similarity index 100%
rename from surfaces/test_functions/griewank_function.py
rename to surfaces/mathematical_functions/griewank_function.py
diff --git a/surfaces/test_functions/himmelblaus_function.py b/surfaces/mathematical_functions/himmelblaus_function.py
similarity index 100%
rename from surfaces/test_functions/himmelblaus_function.py
rename to surfaces/mathematical_functions/himmelblaus_function.py
diff --git "a/surfaces/test_functions/h\303\266lder_table_function.py" "b/surfaces/mathematical_functions/h\303\266lder_table_function.py"
similarity index 100%
rename from "surfaces/test_functions/h\303\266lder_table_function.py"
rename to "surfaces/mathematical_functions/h\303\266lder_table_function.py"
diff --git a/surfaces/test_functions/langermann_function.py b/surfaces/mathematical_functions/langermann_function.py
similarity index 100%
rename from surfaces/test_functions/langermann_function.py
rename to surfaces/mathematical_functions/langermann_function.py
diff --git a/surfaces/test_functions/levi_function_n13.py b/surfaces/mathematical_functions/levi_function_n13.py
similarity index 100%
rename from surfaces/test_functions/levi_function_n13.py
rename to surfaces/mathematical_functions/levi_function_n13.py
diff --git a/surfaces/test_functions/matyas_function.py b/surfaces/mathematical_functions/matyas_function.py
similarity index 100%
rename from surfaces/test_functions/matyas_function.py
rename to surfaces/mathematical_functions/matyas_function.py
diff --git a/surfaces/test_functions/mccormick_function.py b/surfaces/mathematical_functions/mccormick_function.py
similarity index 100%
rename from surfaces/test_functions/mccormick_function.py
rename to surfaces/mathematical_functions/mccormick_function.py
diff --git a/surfaces/test_functions/rastrigin_function.py b/surfaces/mathematical_functions/rastrigin_function.py
similarity index 100%
rename from surfaces/test_functions/rastrigin_function.py
rename to surfaces/mathematical_functions/rastrigin_function.py
diff --git a/surfaces/test_functions/rosenbrock_function.py b/surfaces/mathematical_functions/rosenbrock_function.py
similarity index 100%
rename from surfaces/test_functions/rosenbrock_function.py
rename to surfaces/mathematical_functions/rosenbrock_function.py
diff --git a/surfaces/test_functions/schaffer_function_n2.py b/surfaces/mathematical_functions/schaffer_function_n2.py
similarity index 100%
rename from surfaces/test_functions/schaffer_function_n2.py
rename to surfaces/mathematical_functions/schaffer_function_n2.py
diff --git a/surfaces/test_functions/simionescu_function.py b/surfaces/mathematical_functions/simionescu_function.py
similarity index 100%
rename from surfaces/test_functions/simionescu_function.py
rename to surfaces/mathematical_functions/simionescu_function.py
diff --git a/surfaces/test_functions/sphere_function.py b/surfaces/mathematical_functions/sphere_function.py
similarity index 71%
rename from surfaces/test_functions/sphere_function.py
rename to surfaces/mathematical_functions/sphere_function.py
index 817645e..f8185f2 100644
--- a/surfaces/test_functions/sphere_function.py
+++ b/surfaces/mathematical_functions/sphere_function.py
@@ -10,6 +10,12 @@ class SphereFunction(ObjectiveFunction):
     _name_ = "sphere_function"
     __name__ = "SphereFunction"
 
+    explanation = """The Sphere function has d local minima except for the global one. It is continuous, convex and unimodal. The plot shows its two-dimensional form."""
+
+    dimensions = "n"
+    formula = r"f(\vec{x}) = \sum^n_{i=1}x^2_i"
+    global_minimum = r"f(\vec{x}=0) = 0"
+
     def __init__(self, n_dim, A=1, metric="score", input_type="dictionary", sleep=0):
         super().__init__(metric, input_type, sleep)
         self.n_dim = n_dim
diff --git a/surfaces/test_functions/styblinski_tang_function.py b/surfaces/mathematical_functions/styblinski_tang_function.py
similarity index 100%
rename from surfaces/test_functions/styblinski_tang_function.py
rename to surfaces/mathematical_functions/styblinski_tang_function.py
diff --git a/surfaces/test_functions/three_hump_camel_function.py b/surfaces/mathematical_functions/three_hump_camel_function.py
similarity index 100%
rename from surfaces/test_functions/three_hump_camel_function.py
rename to surfaces/mathematical_functions/three_hump_camel_function.py