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  2. Standard normal table - Wikipedia

    en.wikipedia.org/wiki/Standard_normal_table

    To find a negative value such as –0.83, one could use a cumulative table for negative z-values [3] which yield a probability of 0.20327. But since the normal distribution curve is symmetrical, probabilities for only positive values of Z are typically given.

  3. Letter frequency - Wikipedia

    en.wikipedia.org/wiki/Letter_frequency

    The California Job Case was a compartmentalized box for printing in the 19th century, sizes corresponding to the commonality of letters. The frequency of letters in text has been studied for use in cryptanalysis, and frequency analysis in particular, dating back to the Arab mathematician al-Kindi (c. AD 801–873 ), who formally developed the method (the ciphers breakable by this technique go ...

  4. Smith chart - Wikipedia

    en.wikipedia.org/wiki/Smith_chart

    Therefore, transformations P 1 to Q 1 and P 3 to Q 3 are from the Z Smith chart to the Y Smith chart and transformation Q 2 to P 2 is from the Y Smith chart to the Z Smith chart. The following table shows the steps taken to work through the remaining components and transformations, returning eventually back to the centre of the Smith chart and ...

  5. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    Canadian Table of Frequency Allocations Archived 2008-12-09 at the Wayback Machine (from Industry Canada) U.S. Frequency Allocation Chart – Covering the range 3 kHz to 300 GHz (from Department of Commerce) UK frequency allocation table (from Ofcom, which inherited the Radiocommunications Agency's duties, pdf format)

  6. Redshift - Wikipedia

    en.wikipedia.org/wiki/Redshift

    The largest-observed redshift, corresponding to the greatest distance and furthest back in time, is that of the cosmic microwave background radiation; the numerical value of its redshift is about z = 1089 (z = 0 corresponds to present time), and it shows the state of the universe about 13.8 billion years ago, [63] and 379,000 years after the ...

  7. Frequency (statistics) - Wikipedia

    en.wikipedia.org/wiki/Frequency_(statistics)

    A frequency distribution table is an arrangement of the values that one or more variables take in a sample. Each entry in the table contains the frequency or count of the occurrences of values within a particular group or interval, and in this way, the table summarizes the distribution of values in the sample.

  8. Z-transform - Wikipedia

    en.wikipedia.org/wiki/Z-transform

    In mathematics and signal processing, the Z-transform converts a discrete-time signal, which is a sequence of real or complex numbers, into a complex valued frequency-domain (the z-domain or z-plane) representation. [1] [2] It can be considered a discrete-time equivalent of the Laplace transform (the s-domain or s-plane). [3]

  9. Normal distribution - Wikipedia

    en.wikipedia.org/wiki/Normal_distribution

    If the mean =, the first factor is 1, and the Fourier transform is, apart from a constant factor, a normal density on the frequency domain, with mean 0 and variance ⁠ / ⁠. In particular, the standard normal distribution ⁠ φ {\displaystyle \varphi } ⁠ is an eigenfunction of the Fourier transform.