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  2. Shift-share analysis - Wikipedia

    en.wikipedia.org/wiki/Shift-share_analysis

    Shift-share analysts sometimes use different labels for the three effects, although the calculations are the same. National growth effect may be referred to as national share. [4] [5] Industry mix effect may be referred to as proportional shift. [5] Local share effect may be referred to as differential shift, [3] regional shift, [4] or ...

  3. Finite difference - Wikipedia

    en.wikipedia.org/wiki/Finite_difference

    A finite difference is a mathematical expression of the form f (x + b) − f (x + a).If a finite difference is divided by b − a, one gets a difference quotient.The approximation of derivatives by finite differences plays a central role in finite difference methods for the numerical solution of differential equations, especially boundary value problems.

  4. Shift operator - Wikipedia

    en.wikipedia.org/wiki/Shift_operator

    Shift operator. In mathematics, and in particular functional analysis, the shift operator, also known as the translation operator, is an operator that takes a function x ↦ f(x) to its translation x ↦ f(x + a). [1] In time series analysis, the shift operator is called the lag operator. Shift operators are examples of linear operators ...

  5. Phase-shift keying - Wikipedia

    en.wikipedia.org/wiki/Phase-shift_keying

    OFDM. FDM. Multiplexing. v. t. e. Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication.

  6. Jacobian matrix and determinant - Wikipedia

    en.wikipedia.org/wiki/Jacobian_matrix_and...

    The linear map h → J(x) ⋅ h is known as the derivative or the differential of f at x. When m = n, the Jacobian matrix is square, so its determinant is a well-defined function of x, known as the Jacobian determinant of f. It carries important information about the local behavior of f.

  7. Group delay and phase delay - Wikipedia

    en.wikipedia.org/wiki/Group_delay_and_phase_delay

    The differential group delay is the difference in propagation time between the two eigenmodes X and Y polarizations. Consider two eigenmodes that are the 0° and 90° linear polarization states. If the state of polarization of the input signal is the linear state at 45° between the two eigenmodes, the input signal is divided equally into the ...

  8. Delay differential equation - Wikipedia

    en.wikipedia.org/wiki/Delay_differential_equation

    In mathematics, delay differential equations (DDEs) are a type of differential equation in which the derivative of the unknown function at a certain time is given in terms of the values of the function at previous times. DDEs are also called time-delay systems, systems with aftereffect or dead-time, hereditary systems, equations with deviating ...

  9. Transfer function - Wikipedia

    en.wikipedia.org/wiki/Transfer_function

    Transfer function. In engineering, a transfer function (also known as system function[1] or network function) of a system, sub-system, or component is a mathematical function that models the system's output for each possible input. [2][3][4] It is widely used in electronic engineering tools like circuit simulators and control systems.