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Calculating History
Welcome
An early IT disaster
Bamboo slide rule
Checksum calculators
Reumhelm
Verhoeff
“Casting out nines” and “casting out elevens”
Chemical slide rules
Early chemical slide rules
Christmas tree formulas
Complex number slide rules
Trig formulas using complex numbers
Computing linkages
Antonin Svoboda Patents
Error graphs
Overlays
RE: Computing Linkages
Correlation machines
Appendix: Calculating a correlation coefficient
Doomsday
Animation of a Dutch Radiac
Animation of a Nuclear Bomb Effects Calculator
Dump trucks
Egg slide rule
Electrical slide rules
Electrical Slide Rules Patents
Infinite scales
Irish logarithms
Irish Logarithms Part 2
Jacobi indices
Is that a slide rule in your pocket?
Keyboard
Hofgaard Patents
Lack of space
Davis and Son Patents
Otis King
Patents
Amtsblatt zur Wiener Zeitung
Patents heatmap
Patents per country
Searching trademarks and logos
Terminology
The Cycloop
Mystic Number Machine
Scarcity
Strange table
Decimal system
Rubberized hair
Finnish timber slide rule
Gerber Equameter
Calculating History
Hofgaard Patents
This list of patents by Rolf Hofgaard is extracted from the
Rechnerlexikon
.
Hofgaard Patents
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