GUI.py

import streamlit as st
from muller import muller

def inject_custom_css():
    st.markdown(
        """
        <style>
        /* Style headers within markdown */
        .stMarkdown h1, .stMarkdown h2 {
            color: #00A1FF !important; /* Primary blue for headers in markdown */
        }

        /* Style buttons */
        div.stButton > button {
            background-color: #00A1FF !important;  /* Primary blue */
            color: white !important;
            border-radius: 8px !important;
            font-size: 16px !important;
            font-weight: bold !important;
            border: none !important;
            transition: 0.3s !important;
        }
        div.stButton > button:hover {
            background-color: #007ACC !important; /* Darker blue on hover */
        }

        /* Style input fields */
        input[type="text"], input[type="number"], textarea {
            border: 2px solid #00A1FF !important;
            border-radius: 5px !important;
            padding: 8px !important;
            font-size: 14px !important;
        }
        input[type="text"]:focus, input[type="number"]:focus, textarea:focus {
            outline: none !important;
            border: 2px solid #007ACC !important; /* Darker blue on focus */
        }

        /* Adjust block container for visual improvement */
        .block-container {
            background-color: #F5F5F5 !important;
            padding: 20px !important;
            border-radius: 10px !important;
        }
        </style>
        """,
        unsafe_allow_html=True
    )

# Inject the CSS at the start of the app
inject_custom_css()

# Streamlit App
def muller_app():
    st.title("Numerical Methods Solver: Muller Method (Step-by-Step)")
    st.write("This app calculates the intermediate values for each iteration using the Muller method.")

    # User inputs
    equation = st.text_input(
        "Enter the function f(x):",
        placeholder="e.g., x**3 - 6*x + 8",
        help="Use 'x' for the variable and '**' for exponents. Example: x**3 - 6*x + 8",
    ).strip()
    x0 = st.text_input(
        "Enter the first initial guess (x0):",
        placeholder="e.g., 1+2i for complex or 1 for real numbers"
    ).strip()
    x1 = st.text_input(
        "Enter the second initial guess (x1):",
        placeholder="e.g., 2+i for complex or 2 for real numbers"
    ).strip()
    x2 = st.text_input(
        "Enter the third initial guess (x2):",
        placeholder="e.g., 3+0i for complex or 3 for real numbers"
    ).strip()
    max_iter = st.number_input("Maximum Iterations:", value=10, step=1)
    true_root = st.text_input(
        "Enter the true root (optional):",
        placeholder="e.g., 2+0i for complex or 2 for real numbers",
        help="If known, enter the true root to calculate Et (%) for each iteration.",
    ).strip()

    # Collect errors
    errors = []
    if not equation:
        errors.append("Please enter a valid equation.")
    if not x0:
        errors.append("Please enter a valid initial guess for x0.")
    if not x1:
        errors.append("Please enter a valid initial guess for x1.")
    if not x2:
        errors.append("Please enter a valid initial guess for x2.")

    if st.button("Solve Step-by-Step"):
        # If there are errors, display them all
        if errors:
            for error in errors:
                st.error(error)
            return

        try:
            # Clean and validate the equation
            f = lambda x: eval(equation.replace("^", "**"))  # Replace ^ with ** for exponentiation
            f(1)  # Test the equation with a sample value to validate correctness

            # Parse inputs
            x0 = complex(x0.replace("i", "j"))
            x1 = complex(x1.replace("i", "j"))
            x2 = complex(x2.replace("i", "j"))
            true_root = complex(true_root.replace("i", "j")) if true_root else None

            # Solve using the Muller method
            steps = muller(f, x0, x1, x2, max_iter=max_iter, true_root=true_root)

            st.success("Calculation complete. See step-by-step results below.")
            st.write("### Step-by-Step Results:")
            for step in steps:
                st.write(f"**Iteration {step['iteration']}:**")
                st.json(step)

        except SyntaxError:
            st.error("The equation syntax is incorrect. Please check your input.")
        except Exception as e:
            st.error(f"An error occurred: {e}")

if __name__ == "__main__":
    muller_app()