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  2. Decay correction - Wikipedia

    en.wikipedia.org/wiki/Decay_correction

    Decay correction is one way of working out what the radioactivity would have been at the time it was taken, rather than at the time it was tested. For example, the isotope copper-64, commonly used in medical research, has a half-life of 12.7 hours. If you inject a large group of animals at "time zero", but measure the radioactivity in their ...

  3. Rand index - Wikipedia

    en.wikipedia.org/wiki/Rand_index

    The calculated Adjusted Rand index for these two clusterings is. The Rand index [1] or Rand measure (named after William M. Rand) in statistics, and in particular in data clustering, is a measure of the similarity between two data clusterings. A form of the Rand index may be defined that is adjusted for the chance grouping of elements, this is ...

  4. Aberration (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Aberration_(astronomy)

    Aberration (astronomy) A diagram showing how the apparent position of a star viewed from the Earth can change depending on the Earth's velocity. The effect is typically much smaller than illustrated. In astronomy, aberration (also referred to as astronomical aberration, stellar aberration, or velocity aberration) is a phenomenon where celestial ...

  5. Prism (geometry) - Wikipedia

    en.wikipedia.org/wiki/Prism_(geometry)

    An oblique prism is a prism in which the joining edges and faces are not perpendicular to the base faces. Example: a parallelepiped is an oblique prism whose base is a parallelogram, or equivalently a polyhedron with six parallelogram faces. Right Prism. A right prism is a prism in which the joining edges and faces are perpendicular to the base ...

  6. Euler's formula - Wikipedia

    en.wikipedia.org/wiki/Euler's_formula

    Euler's formula, named after Leonhard Euler, is a mathematical formula in complex analysis that establishes the fundamental relationship between the trigonometric functions and the complex exponential function. Euler's formula states that, for any real number x, one has. where e is the base of the natural logarithm, i is the imaginary unit, and ...

  7. Fourier transform - Wikipedia

    en.wikipedia.org/wiki/Fourier_transform

    In physics, engineeringand mathematics, the Fourier transform(FT) is an integral transformthat takes a functionas input and outputs another function that describes the extent to which various frequencies are present in the original function. The output of the transform is a complex-valued function of frequency.

  8. Wedge prism - Wikipedia

    en.wikipedia.org/wiki/Wedge_prism

    Wedge prism. The wedge prism is a prism with a shallow angle between its input and output surfaces. This angle is usually 3 degrees or less. Refraction at the surfaces causes the prism to deflect light by a fixed angle. When viewing a scene through such a prism, objects will appear to be offset by an amount that varies with their distance from ...

  9. Gamma correction - Wikipedia

    en.wikipedia.org/wiki/Gamma_correction

    Gamma correction is a type of power law function whose exponent is the Greek letter gamma ( γ ). It should not be confused with the mathematical Gamma function. The lower case gamma, γ, is a parameter of the former; the upper case letter, Γ, is the name of (and symbol used for) the latter (as in Γ ( x )).