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  2. Trapezoidal rule - Wikipedia

    en.wikipedia.org/wiki/Trapezoidal_rule

    In calculus, the trapezoidal rule (also known as the trapezoid rule or trapezium rule) [a] is a technique for numerical integration, i.e., approximating the definite integral: (). The trapezoidal rule works by approximating the region under the graph of the function f ( x ) {\displaystyle f(x)} as a trapezoid and calculating its area.

  3. Square wave - Wikipedia

    en.wikipedia.org/wiki/Square_wave

    (Odd) harmonics of a 1000 Hz square wave Graph showing the first 3 terms of the Fourier series of a square wave Using Fourier expansion with cycle frequency f over time t , an ideal square wave with an amplitude of 1 can be represented as an infinite sum of sinusoidal waves: x ( t ) = 4 π ∑ k = 1 ∞ sin ⁡ ( 2 π ( 2 k − 1 ) f t ) 2 k ...

  4. Sum of squares - Wikipedia

    en.wikipedia.org/wiki/Sum_of_squares

    The squared Euclidean distance between two points, equal to the sum of squares of the differences between their coordinates; Heron's formula for the area of a triangle can be re-written as using the sums of squares of a triangle's sides (and the sums of the squares of squares) The British flag theorem for rectangles equates two sums of two ...

  5. Numerical integration - Wikipedia

    en.wikipedia.org/wiki/Numerical_integration

    The ancient Babylonians used the trapezoidal rule to integrate the motion of Jupiter along the ecliptic. [3] Antique method to find the Geometric mean. For a quadrature of a rectangle with the sides a and b it is necessary to construct a square with the side = (the Geometric mean of a and b).

  6. Trapezoid - Wikipedia

    en.wikipedia.org/wiki/Trapezoid

    A right trapezoid (also called right-angled trapezoid) has two adjacent right angles. [15] Right trapezoids are used in the trapezoidal rule for estimating areas under a curve. An acute trapezoid has two adjacent acute angles on its longer base edge. An obtuse trapezoid on the other hand has one acute and one obtuse angle on each base.

  7. Riemann sum - Wikipedia

    en.wikipedia.org/wiki/Riemann_sum

    While not derived as a Riemann sum, taking the average of the left and right Riemann sums is the trapezoidal rule and gives a trapezoidal sum. It is one of the simplest of a very general way of approximating integrals using weighted averages. This is followed in complexity by Simpson's rule and Newton–Cotes formulas.

  8. Fermat's theorem on sums of two squares - Wikipedia

    en.wikipedia.org/wiki/Fermat's_theorem_on_sums_of...

    For the avoidance of ambiguity, zero will always be a valid possible constituent of "sums of two squares", so for example every square of an integer is trivially expressible as the sum of two squares by setting one of them to be zero. 1. The product of two numbers, each of which is a sum of two squares, is itself a sum of two squares.

  9. Newton–Cotes formulas - Wikipedia

    en.wikipedia.org/wiki/Newton–Cotes_formulas

    It is assumed that the value of a function f defined on [,] is known at + equally spaced points: < < <.There are two classes of Newton–Cotes quadrature: they are called "closed" when = and =, i.e. they use the function values at the interval endpoints, and "open" when > and <, i.e. they do not use the function values at the endpoints.