You wouldn't have GPS if it weren't for this algorithm

Many of the inventors who fueled the digital revolution have become household names. Innovators such as Steve Jobs, Bill Gates, and Mark Zuckerberg all contributed mightily to the technologies that have transformed our daily lives and society. If you're not an engineer, however, you have probably never heard of the brilliant inventor Rudolf Kálmán, a Budapest-born engineer and mathematician who died on July 2 in Gainesville, Florida, at age 86. His fundamental contribution, an algorithm called the Kalman filter, made possible many essential technological achievements of the last 50 years. These include aerospace systems such as the computers that landed Apollo astronauts on the moon, robotic vehicles that explore our world from the deep sea to the outer planets, and nearly any endeavor that needs to estimate the state of the world from noisy data. Someone once described the entire GPS system--an Earth-girdling constellation of satellites, ground stations, and computers as "one enormous Kalman filter."