From cdc06756de0a663a37e47505dabc0c57a3b7acde Mon Sep 17 00:00:00 2001
From: AngleAirdrop <92680828+AngleAirdrop@users.noreply.github.com>
Date: Fri, 31 Oct 2025 21:30:16 +0700
Subject: [PATCH] MathToolkit.java

---
 .../com/thealgorithms/maths/MathToolkit.java  | 313 ++++++++++++++++++
 1 file changed, 313 insertions(+)
 create mode 100644 src/main/java/com/thealgorithms/maths/MathToolkit.java

diff --git a/src/main/java/com/thealgorithms/maths/MathToolkit.java b/src/main/java/com/thealgorithms/maths/MathToolkit.java
new file mode 100644
index 000000000000..f30680f9c0f0
--- /dev/null
+++ b/src/main/java/com/thealgorithms/maths/MathToolkit.java
@@ -0,0 +1,313 @@
+/*
+ * MathToolkit.java
+ * A simple single-file Java project that provides a command-line math toolkit.
+ * All user-facing text is in English as requested.
+ *
+ * Features:
+ *  - Basic arithmetic (addition, subtraction, multiplication, division)
+ *  - GCD and LCM
+ *  - Factorial (uses BigInteger for large results)
+ *  - Fibonacci (n-th, uses BigInteger)
+ *  - Prime check (BigInteger.isProbablePrime)
+ *  - Quadratic equation solver (real and complex roots)
+ *
+ * Usage:
+ *  Compile: javac MathToolkit.java
+ *  Run:     java MathToolkit
+ *
+ * Author: ChatGPT
+ */
+
+import java.math.BigInteger;
+import java.util.InputMismatchException;
+import java.util.Scanner;
+
+public class MathToolkit {
+
+    private static final Scanner scanner = new Scanner(System.in);
+
+    public static void main(String[] args) {
+        System.out.println("Welcome to MathToolkit — a simple Java math project.");
+        boolean running = true;
+        while (running) {
+            printMenu();
+            System.out.print("Choose an option (1-9) or 0 to exit: ");
+            int choice = readInt();
+            System.out.println();
+            switch (choice) {
+                case 0:
+                    running = false;
+                    System.out.println("Goodbye!");
+                    break;
+                case 1:
+                    basicArithmetic();
+                    break;
+                case 2:
+                    gcdLcm();
+                    break;
+                case 3:
+                    factorial();
+                    break;
+                case 4:
+                    fibonacci();
+                    break;
+                case 5:
+                    primeCheck();
+                    break;
+                case 6:
+                    quadraticSolver();
+                    break;
+                case 7:
+                    integerOperationsDemo();
+                    break;
+                case 8:
+                    about();
+                    break;
+                case 9:
+                    help();
+                    break;
+                default:
+                    System.out.println("Invalid option — please try again.");
+            }
+            System.out.println();
+        }
+        scanner.close();
+    }
+
+    private static void printMenu() {
+        System.out.println("=== MathToolkit Menu ===");
+        System.out.println("1) Basic arithmetic ( +, -, *, / )");
+        System.out.println("2) GCD and LCM");
+        System.out.println("3) Factorial (BigInteger)");
+        System.out.println("4) Fibonacci (n-th term, BigInteger)");
+        System.out.println("5) Prime check");
+        System.out.println("6) Quadratic equation solver");
+        System.out.println("7) Integer operations demo (safe long handling)");
+        System.out.println("8) About this project");
+        System.out.println("9) Help (short usage)");
+        System.out.println("0) Exit");
+    }
+
+    private static void basicArithmetic() {
+        System.out.println("-- Basic arithmetic --");
+        System.out.print("Enter first number: ");
+        double a = readDouble();
+        System.out.print("Enter second number: ");
+        double b = readDouble();
+        System.out.println("Choose operator: +  -  *  /");
+        System.out.print("Operator: ");
+        String op = scanner.next();
+        double result;
+        switch (op) {
+            case "+":
+                result = a + b;
+                System.out.printf("Result: %.10g\n", result);
+                break;
+            case "-":
+                result = a - b;
+                System.out.printf("Result: %.10g\n", result);
+                break;
+            case "*":
+                result = a * b;
+                System.out.printf("Result: %.10g\n", result);
+                break;
+            case "/":
+                if (b == 0) {
+                    System.out.println("Error: Division by zero is not allowed.");
+                } else {
+                    result = a / b;
+                    System.out.printf("Result: %.10g\n", result);
+                }
+                break;
+            default:
+                System.out.println("Unknown operator.");
+        }
+    }
+
+    private static void gcdLcm() {
+        System.out.println("-- GCD and LCM --");
+        System.out.print("Enter first integer (long): ");
+        long a = readLong();
+        System.out.print("Enter second integer (long): ");
+        long b = readLong();
+        long g = gcd(a, b);
+        long l = lcm(a, b);
+        System.out.println("GCD(" + a + ", " + b + ") = " + g);
+        System.out.println("LCM(" + a + ", " + b + ") = " + l);
+    }
+
+    private static void factorial() {
+        System.out.println("-- Factorial --");
+        System.out.print("Enter a non-negative integer (n): ");
+        int n = readNonNegativeInt();
+        BigInteger fact = factorialBig(n);
+        System.out.println(n + "! = " + fact.toString());
+    }
+
+    private static void fibonacci() {
+        System.out.println("-- Fibonacci (n-th) --");
+        System.out.print("Enter n (0-based index, non-negative): ");
+        int n = readNonNegativeInt();
+        BigInteger fib = fibonacciBig(n);
+        System.out.println("Fibonacci(" + n + ") = " + fib.toString());
+    }
+
+    private static void primeCheck() {
+        System.out.println("-- Prime check --");
+        System.out.print("Enter integer to check (positive): ");
+        long n = readLongPositive();
+        BigInteger big = BigInteger.valueOf(n);
+        boolean probablePrime = big.isProbablePrime(12); // 12 -> sufficiently small error probability
+        if (probablePrime) {
+            System.out.println(n + " is probably prime.");
+        } else {
+            System.out.println(n + " is composite (not prime).");
+        }
+    }
+
+    private static void quadraticSolver() {
+        System.out.println("-- Quadratic equation solver: ax^2 + bx + c = 0 --");
+        System.out.print("Enter a (non-zero): ");
+        double a = readDoubleNonZero();
+        System.out.print("Enter b: ");
+        double b = readDouble();
+        System.out.print("Enter c: ");
+        double c = readDouble();
+        double disc = b * b - 4 * a * c;
+        if (disc > 0) {
+            double r1 = (-b + Math.sqrt(disc)) / (2 * a);
+            double r2 = (-b - Math.sqrt(disc)) / (2 * a);
+            System.out.printf("Two real roots: x1 = %.10g, x2 = %.10g\n", r1, r2);
+        } else if (disc == 0) {
+            double r = -b / (2 * a);
+            System.out.printf("One real root: x = %.10g\n", r);
+        } else {
+            double real = -b / (2 * a);
+            double imag = Math.sqrt(-disc) / (2 * a);
+            System.out.printf("Two complex roots: x1 = %.10g + %.10gi, x2 = %.10g - %.10gi\n", real, imag, real, imag);
+        }
+    }
+
+    private static void integerOperationsDemo() {
+        System.out.println("-- Integer operations demo --");
+        System.out.println("This demonstrates safe handling with long and BigInteger when needed.");
+        System.out.print("Enter a long integer: ");
+        long a = readLong();
+        System.out.print("Enter another long integer: ");
+        long b = readLong();
+        System.out.println("Sum as long: " + (a + b));
+        BigInteger bigSum = BigInteger.valueOf(a).add(BigInteger.valueOf(b));
+        System.out.println("Sum as BigInteger: " + bigSum.toString());
+    }
+
+    private static void about() {
+        System.out.println("MathToolkit — single-file Java project. All text is English.");
+        System.out.println("Feel free to request additional features or a multi-file project structure.");
+    }
+
+    private static void help() {
+        System.out.println("Help: Use options from the menu, input numbers when asked.");
+        System.out.println("For large factorial or Fibonacci values, the program uses BigInteger.");
+    }
+
+    // --- Utility math functions ---
+
+    private static long gcd(long a, long b) {
+        a = Math.abs(a);
+        b = Math.abs(b);
+        if (a == 0) return b;
+        if (b == 0) return a;
+        while (b != 0) {
+            long t = a % b;
+            a = b;
+            b = t;
+        }
+        return Math.abs(a);
+    }
+
+    private static long lcm(long a, long b) {
+        a = Math.abs(a);
+        b = Math.abs(b);
+        if (a == 0 || b == 0) return 0;
+        return Math.abs(a / gcd(a, b) * b);
+    }
+
+    private static BigInteger factorialBig(int n) {
+        BigInteger result = BigInteger.ONE;
+        for (int i = 2; i <= n; i++) {
+            result = result.multiply(BigInteger.valueOf(i));
+        }
+        return result;
+    }
+
+    private static BigInteger fibonacciBig(int n) {
+        if (n == 0) return BigInteger.ZERO;
+        if (n == 1) return BigInteger.ONE;
+        BigInteger prev = BigInteger.ZERO, curr = BigInteger.ONE;
+        for (int i = 2; i <= n; i++) {
+            BigInteger next = prev.add(curr);
+            prev = curr;
+            curr = next;
+        }
+        return curr;
+    }
+
+    // --- Robust input helpers ---
+
+    private static int readInt() {
+        while (true) {
+            try {
+                return scanner.nextInt();
+            } catch (InputMismatchException ex) {
+                System.out.print("Invalid integer — please enter again: ");
+                scanner.next();
+            }
+        }
+    }
+
+    private static int readNonNegativeInt() {
+        while (true) {
+            int v = readInt();
+            if (v < 0) System.out.print("Please enter a non-negative integer: ");
+            else return v;
+        }
+    }
+
+    private static long readLong() {
+        while (true) {
+            try {
+                return scanner.nextLong();
+            } catch (InputMismatchException ex) {
+                System.out.print("Invalid long — please enter again: ");
+                scanner.next();
+            }
+        }
+    }
+
+    private static long readLongPositive() {
+        while (true) {
+            long v = readLong();
+            if (v <= 0) System.out.print("Please enter a positive integer: ");
+            else return v;
+        }
+    }
+
+    private static double readDouble() {
+        while (true) {
+            try {
+                return scanner.nextDouble();
+            } catch (InputMismatchException ex) {
+                System.out.print("Invalid number — please enter again: ");
+                scanner.next();
+            }
+        }
+    }
+
+    private static double readDoubleNonZero() {
+        while (true) {
+            double v = readDouble();
+            if (v == 0.0) System.out.print("Value cannot be zero — please enter again: ");
+            else return v;
+        }
+    }
+}