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# Java programs written by Dario Alpern

The programs in this site are:

1. Generic Two integer variable equation solver: Diophantine equation ax2 + bxy + cy2 + dx + ey + f = 0 solver, where the unknowns x and y can be integer numbers only. Written in Java/JavaScript. Now it includes source code. Last updated on May 31st, 2001.

2. Quadratic modular equation solver: Calculator that can solve equations of the form ax2 + bx + c = 0 (mod n). Last updated: May 2nd, 2002.

3. Ulam's Spiral: Java applet featuring a graphical view of prime numbers. Last updated on March 25th, 2004.

4. Factorization using the Elliptic Curve Method: Applet that can be used to find 20- or 30-digit factors of numbers or numerical expressions up to 10000 digits long. It also computes the number and sum of divisors, Euler's totient and Moebius, and its decomposition as a sum of up to 4 perfect squares. Last updated on August 22nd, 2010.

5. Gaussian Integer Factorization applet: Finds the factors of complex numbers of the form a+bi where a and b are integers. It also includes a complete calculator with operators and functions using gaussian integers. Last updated on June 1st, 2002.

6. Gaussian Primes: Java applet featuring a graphical view of gaussian prime numbers. Last updated on June 15th, 2003.

7. Discrete logarithm calculator: Applet that finds the exponent in the expression BaseExponent = Power (mod Modulus). Last updated on March 30th, 2002.

8. Continued fraction calculator: This calculator can find the continued fraction expansions of rational numbers and quadratic irrationalities. Last updated on April 28th, 2002.

9. Sum of squares: This calculator can find the decomposition of a number or numerical expression in a sum of up to four squares. It does not need its prime factorization. Last updated on November 27th, 2002.

10. GenoJava: Genopro genealogy program add-on that uses Java to display family trees on Internet. Last updated on January 26th, 2003.

11. Polynomial factorization: This calculator can find the decomposition of a polynomial modulo a prime in a product of irreducible factors. Last updated on January 12th, 2005.

12. Big Number scientific calculator: This high-precision calculator features complex numbers, precision up to 1 million digits and exponents up to 1 billion.

13. Distance between cities:

This is the first program that I have written in Java.

It has a database of 105 cities, with their geographic locations. You can get the distance between any two cities of the database.

The program contains two tests. In the first the user must input the distance between two random cities given by the computer (there are ten questions). In the second test there are a departure city, a destination city, and four more. The user should minimize the distance traveled by passing through the six cities.

Press here to run the program

Press here to obtain the source code