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  2. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    The delta function was introduced by physicist Paul Dirac, and has since been applied routinely in physics and engineering to model point masses and instantaneous impulses. It is called the delta function because it is a continuous analogue of the Kronecker delta function, which is usually defined on a discrete domain and takes values 0 and 1.

  3. Delta potential - Wikipedia

    en.wikipedia.org/wiki/Delta_potential

    The delta potential is the potential = (), where δ(x) is the Dirac delta function. It is called a delta potential well if λ is negative, and a delta potential barrier if λ is positive. The delta has been defined to occur at the origin for simplicity; a shift in the delta function's argument does not change any of the following results.

  4. Delta rule - Wikipedia

    en.wikipedia.org/wiki/Delta_rule

    While the delta rule is similar to the perceptron's update rule, the derivation is different. The perceptron uses the Heaviside step function as the activation function g ( h ) {\\displaystyle g(h)} , and that means that g ′ ( h ) {\\displaystyle g'(h)} does not exist at zero, and is equal to zero elsewhere, which makes the direct application ...

  5. List of equations in quantum mechanics - Wikipedia

    en.wikipedia.org/wiki/List_of_equations_in...

    Summarized below are the various forms the Hamiltonian takes, with the corresponding Schrödinger equations and forms of wavefunction solutions. Notice in the case of one spatial dimension, for one particle, the partial derivative reduces to an ordinary derivative .

  6. Green's function - Wikipedia

    en.wikipedia.org/wiki/Green's_function

    Green's functions are also useful tools in solving wave equations and diffusion equations. In quantum mechanics, Green's function of the Hamiltonian is a key concept with important links to the concept of density of states. The Green's function as used in physics is usually defined with the opposite sign, instead.

  7. Kronecker delta - Wikipedia

    en.wikipedia.org/wiki/Kronecker_delta

    The generalized Kronecker delta or multi-index Kronecker delta of order is a type (,) tensor that is completely antisymmetric in its upper indices, and also in its lower indices. Two definitions that differ by a factor of p ! {\displaystyle p!} are in use.

  8. Lambert's problem - Wikipedia

    en.wikipedia.org/wiki/Lambert's_problem

    Stated another way, Lambert's problem is the boundary value problem for the differential equation ¨ = ^ of the two-body problem when the mass of one body is infinitesimal; this subset of the two-body problem is known as the Kepler orbit.

  9. Newmark-beta method - Wikipedia

    en.wikipedia.org/wiki/Newmark-beta_method

    The Newmark-beta method is a method of numerical integration used to solve certain differential equations.It is widely used in numerical evaluation of the dynamic response of structures and solids such as in finite element analysis to model dynamic systems.