new: SHIFT
the most difficult puzzle in the world
last update:
jan 25 - 2011


David E. Dirkse


(x2+y2)(y2+x(x+b))=4axy2
a = 4, b = 5

click your choice below
news / history
freeware
games
articles
Delphi programming
about this site


freeware

name description size
fonttest show pixel image of character program (252kB) download
keystroke display ASCII codes of key program (184kB) download
chrcode display ASCII code of characters program (184kB) download
Polygon Overlap Calculator calculate the area of polygons
and their overlap
330kB specs /
download
Ranks systematically generate
Combinations,Permutations,Partitions
268kB specs /
download
Graphics-
Explorer
plot / compute / explore / print
different types of equations
484kB specs /
download
pinwheel operate a vintage mechanical calculator 313kB descr./
download
factor factorize numbers of up to 18 digits.
Compute GCD
417kB download
lineq solve systems of 2 to 9 equations
use STEP mode to observe step-by-step
process with explanation
303kB download
Euclid solve equations like Ax + By = C
for integers A,B,C,x,y
244kB download
numbers convert numbers to/from
number systems 2..16
233kB download


All freeware :
- executes under Windows 95 and up
- ships as *.exe file
- has no installation procedure
- does not change Windows Registry


games

name description imageaction
Peg Solitaire
version 2
Single Player Puzzle description/
download
Nim Games 9 Nim games
easy to difficult
description/
download
SUDOKU -
helper -
solver
assists in
solving
puzzles
description/
download
CANs - Nim game
- 10 levels
- hall of fame
play
ColorStacks - 7 levels
- hall of fame
- global contest
description
download
connect4 - 8 levels
- 8 strategies
- hall of fame
- analyses
download
new version 4.0

algorithm
description


articles

subject type format
about Triangles and Sides .... plane geometry HTML display
geometric proofs of
trigonometric identities
geometry HTML display
calculate Square Root
using Pencil and Paper
arithmetic / algebra HTML display
Energy Storage physics / calculus HTML display
calculate p algebra HTML/javascript display
the Ultimate Gutter calculus HTML display
calculations in
plane geometry
algebra applications HTML display
Lissajous Curves in motion parametric functions HTML display
the Least Squares method linear algebra application HTML display
a CONNECT4 search algorithm artificial intelligence/
search technique
HTML display
Formula Translation programming algorithm HTML display




Delphi programming

subject type format
the Direction of a vector theory + code + exerciser program HTML / program display
3D spheres painting theory + source code HTML / program display
Flicker free, smooth, painting theory + source code HTML / program display
A Microseconds Counter description + source code HTML display
Fast Drawing in Delphi description + source code + program HTML display
a simple component
for color selection
description + source code HTML display
resizing Bitmaps programming algorithm HTML display
programming the
sudoku helper/solver
Delphi programming HTML display
exponential curve fitting:
y = aebx + c
calculus application /
Delphi programming
HTML display
solving Ax + By = C mathematics/
Delphi programming
HTML display
an ArrayButton Component Delphi programming HTML display
your own Dialog Form Delphi programming HTML display
FloodFill programming algorithm/
Delphi programming
HTML display



About this site
This site is intended for people who are interested in programming and
mathematics (at a high-school level and up).
Programs and articles are the result of my wondering, study and excercise.
Undoubtedly I have reinvented the wheel in many cases.

About myself
Born 1945 in Amsterdam, the Netherlands, I joined "Bull GE" in 1967 as
a junior programmer after a study in electrical engineering.
Eager to learn how computers function and how (on earth) it it possible
for machines to make calculations, soon I switched to Control Data Corporation (CDC).
As a hardware engineer, for almost 25 years I was responsible for installation
and maintenance of mainframes at scientific data centers in the Netherlands.
As such I have witnessed the evolution of computer hardware:
from CDC3300 to 6600 (the first parallel processor) and CYBER205 mainframes.
During this period I attended over 100 technical courses and instructed in more
than 30 occasions.
At the decline of CDC, while finishing large customers, I started
a study of mathematics and became a math teacher in 1993.
My hobby is programming, in particular writing educational software and
solving puzzles.