document main.py and solve constant function problem

Author: HalemoGPA

src/main.py

@@ -16,25 +16,29 @@
 
 
 class FunctionPlotter(QMainWindow):
+    """
+    A class representing the main window for the function plotter application.
+
+    This class handles the GUI elements, user inputs, and plotting of mathematical functions
+    using PySide2 for the GUI and Matplotlib for plotting.
+    """
+
     def __init__(self):
         super().__init__()
         self.setWindowTitle("Function Plotter")
 
-        # Central widget
+        # Initialize the central widget and main layout
         self.central_widget = QWidget()
         self.setCentralWidget(self.central_widget)
-
-        # Layouts
         self.layout = QVBoxLayout()
         self.input_layout = QHBoxLayout()
         self.central_widget.setLayout(self.layout)
 
-        # Function input
+        # Initialize input fields for the function and range values
         self.function_input = QLineEdit()
         self.function_input.setPlaceholderText("Enter function of x, e.g., 5*x^3 + 2*x")
         self.input_layout.addWidget(self.function_input)
 
-        # Min and max inputs
         self.min_input = QLineEdit()
         self.min_input.setPlaceholderText("Enter min value of x")
         self.input_layout.addWidget(self.min_input)
@@ -45,19 +49,21 @@ def __init__(self):
 
         self.layout.addLayout(self.input_layout)
 
-        # Plot button
+        # Initialize the plot button
         self.plot_button = QPushButton("Plot Function")
         self.plot_button.clicked.connect(self.plot_function)
         self.layout.addWidget(self.plot_button)
 
-        # Matplotlib figure
+        # Initialize the Matplotlib figure and canvas
         self.figure, self.ax = plt.subplots()
         self.canvas = FigureCanvas(self.figure)
         self.layout.addWidget(self.canvas)
 
     def plot_function(self):
-        function = self.function_input.text()
-        function = function.replace(" ", "")
+        """
+        Handles the plotting of the function based on user inputs.
+        """
+        function = self.function_input.text().replace(" ", "")
         min_x = self.min_input.text()
         max_x = self.max_input.text()
 
@@ -67,7 +73,12 @@ def plot_function(self):
 
         try:
             min_x = float(min_x)
+            # Make range from -1e20 to 1e20 whatever the input
+            min_x = max(min(1e20, min_x), -1e20)
             max_x = float(max_x)
+            # Make range from -1e20 to 1e20 whatever the input
+            max_x = max(min(1e20, max_x), -1e20)
+
         except ValueError:
             self.show_error_message("Min and Max values must be numbers.")
             return
@@ -89,7 +100,7 @@ def plot_function(self):
             self.show_error_message(f"Error in function evaluation: {e}")
             return
 
-        # Clear previous plot
+        # Clear previous plot and plot new function
         self.ax.clear()
         self.ax.plot(x, y)
         self.ax.set_title(f"Plot of {function}")
@@ -98,6 +109,17 @@ def plot_function(self):
         self.canvas.draw()
 
     def validate_inputs(self, function, min_x, max_x):
+        """
+        Validates the user inputs for the function and range values.
+
+        Parameters:
+        - function (str): The mathematical function entered by the user.
+        - min_x (str): The minimum value of x entered by the user.
+        - max_x (str): The maximum value of x entered by the user.
+
+        Returns:
+        - bool: True if inputs are valid, False otherwise.
+        """
         if not function:
             self.show_error_message("Function cannot be empty.")
             return False
@@ -113,12 +135,31 @@ def validate_inputs(self, function, min_x, max_x):
         return True
 
     def prepare_function(self, function, x):
+        """
+        Prepares the function for evaluation by replacing operators with their numpy equivalents.
+
+        Parameters:
+        - function (str): The mathematical function entered by the user.
+        - x (np.ndarray): The array of x values.
+
+        Returns:
+        - str: The prepared function.
+        """
         function = function.replace("^", "**")
         function = function.replace("log10", "np.log10")
         function = function.replace("sqrt", "np.sqrt")
+        # if function is a constant (e.g. y=5)
+        if "x" not in function:
+            function = f"{function}*np.ones_like(x)"
         return function
 
     def show_error_message(self, message):
+        """
+        Displays an error message dialog.
+
+        Parameters:
+        - message (str): The error message to display.
+        """
         QMessageBox.critical(self, "Error", message)