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The teeth are moved by a second wheel located inside the first and moved by a side lever. A pinwheel calculator is a class of mechanical calculator described as early as 1685, and popular in the 19th and 20th century, calculating via wheels whose number of teeth were adjustable. These wheels, also called pinwheels, could be set by using a side ...
History. The Curta was conceived by Curt Herzstark in the 1930s in Vienna, Austria.By 1938, he had filed a key patent, covering his complemented stepped drum. This single drum replaced the multiple drums, typically around 10 or so, of contemporary calculators, and it enabled not only addition, but subtraction through nines complement math, essentially subtracting by adding.
This picture shows clockwise from top left: An Arithmometer, a Comptometer, a Dalton adding machine, a Sundstrand, and an Odhner Arithmometer. A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or (historically) a simulation such as an analog computer or a ...
Little Professor. Little Professor with accompanying booklet. The Little Professor is a backwards-functioning calculator designed for children ages 5 to 9. Instead of providing the answer to a mathematical expression entered by the user, it generates unsolved expressions and prompts the user for the answer. [1]
A scientific calculator is an electronic calculator, either desktop or handheld, designed to perform calculations using basic ( addition, subtraction, multiplication, division) and complex ( trigonometric, hyperbolic, etc.) mathematical operations and functions. They have completely replaced slide rules as well as books of mathematical tables ...
In statistics, the jackknife (jackknife cross-validation) is a cross-validation technique and, therefore, a form of resampling . It is especially useful for bias and variance estimation. The jackknife pre-dates other common resampling methods such as the bootstrap. Given a sample of size , a jackknife estimator can be built by aggregating the ...
In statistics, an estimator is a rule for calculating an estimate of a given quantity based on observed data: thus the rule (the estimator), the quantity of interest (the estimand) and its result (the estimate) are distinguished. [1] For example, the sample mean is a commonly used estimator of the population mean .
Convergence definitions. Suppose that the sequence converges to the number . The sequence is said to converge with order to , and with a rate of convergence [3] of , if. (Definition 1) for some positive constant if , and if . [4] [5] It is not necessary, however, that be an integer.