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  2. Sellmeier equation - Wikipedia

    en.wikipedia.org/wiki/Sellmeier_equation

    For common optical glasses, the refractive index calculated with the three-term Sellmeier equation deviates from the actual refractive index by less than 5×10 −6 over the wavelengths' range [5] of 365 nm to 2.3 μm, which is of the order of the homogeneity of a glass sample. [6]

  3. Time derivative - Wikipedia

    en.wikipedia.org/wiki/Time_derivative

    A time derivative is a derivative of a function with respect to time, usually interpreted as the rate of change of the value of the function. [1] The variable denoting time is usually written as t {\displaystyle t} .

  4. Numerical differentiation - Wikipedia

    en.wikipedia.org/wiki/Numerical_differentiation

    Therefore, the true derivative of f at x is the limit of the value of the difference quotient as the secant lines get closer and closer to being a tangent line: ′ = (+) (). Since immediately substituting 0 for h results in 0 0 {\displaystyle {\frac {0}{0}}} indeterminate form , calculating the derivative directly can be unintuitive.

  5. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    As another example, consider a distribution in which 6/10 of the time returns a standard normal distribution, and 4/10 of the time returns exactly the value 3.5 (i.e. a partly continuous, partly discrete mixture distribution). The density function of this distribution can be written as

  6. Crank–Nicolson method - Wikipedia

    en.wikipedia.org/wiki/Crank–Nicolson_method

    The Crank–Nicolson stencil for a 1D problem. The Crank–Nicolson method is based on the trapezoidal rule, giving second-order convergence in time.For linear equations, the trapezoidal rule is equivalent to the implicit midpoint method [citation needed] —the simplest example of a Gauss–Legendre implicit Runge–Kutta method—which also has the property of being a geometric integrator.

  7. Exponential distribution - Wikipedia

    en.wikipedia.org/wiki/Exponential_distribution

    In probability theory and statistics, the exponential distribution or negative exponential distribution is the probability distribution of the distance between events in a Poisson point process, i.e., a process in which events occur continuously and independently at a constant average rate; the distance parameter could be any meaningful mono-dimensional measure of the process, such as time ...

  8. Fréchet distribution - Wikipedia

    en.wikipedia.org/wiki/Fréchet_distribution

    The Fréchet distribution, also known as inverse Weibull distribution, [2] [3] is a special case of the generalized extreme value distribution. It has the cumulative distribution function It has the cumulative distribution function

  9. FTCS scheme - Wikipedia

    en.wikipedia.org/wiki/FTCS_scheme

    The function must be discretized spatially with a central difference scheme. This is an explicit method which means that, u i n + 1 {\displaystyle u_{i}^{n+1}} can be explicitly computed (no need of solving a system of algebraic equations) if values of u {\displaystyle u} at previous time level ( n ) {\displaystyle (n)} are known.