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The logarithmic Schrödinger equation is a partial differential equation.In mathematics and mathematical physics one often uses its dimensionless form: + + | | = for the complex-valued function ψ = ψ(x, t) of the particles position vector x = (x, y, z) at time t, and = + + is the Laplacian of ψ in Cartesian coordinates.
A logarithmic unit is a unit that can be used to express a quantity (physical or mathematical) on a logarithmic scale, that is, as being proportional to the value of a logarithm function applied to the ratio of the quantity and a reference quantity of the same type. The choice of unit generally indicates the type of quantity and the base of the ...
Scientific quantities are often expressed as logarithms of other quantities, using a logarithmic scale. For example, the decibel is a unit of measurement associated with logarithmic-scale quantities. It is based on the common logarithm of ratios—10 times the common logarithm of a power ratio or 20 times the common logarithm of a voltage ratio.
Note the logarithmic scale markings on each of the axes, and that the log x and log y axes (where the logarithms are 0) are where x and y themselves are 1. Comparison of linear, concave, and convex functions when plotted using a linear scale (left) or a log scale (right).
The logarithmic decrement can be obtained e.g. as ln(x 1 /x 3).Logarithmic decrement, , is used to find the damping ratio of an underdamped system in the time domain.. The method of logarithmic decrement becomes less and less precise as the damping ratio increases past about 0.5; it does not apply at all for a damping ratio greater than 1.0 because the system is overdamped.
Logarithms can be used to make calculations easier. For example, two numbers can be multiplied just by using a logarithm table and adding. These are often known as logarithmic properties, which are documented in the table below. [2] The first three operations below assume that x = b c and/or y = b d, so that log b (x) = c and log b (y) = d.
The logarithm keys (log for base-10 and ln for base-e) on a typical scientific calculator. The advent of hand-held calculators largely eliminated the use of common logarithms as an aid to computation. The numerical value for logarithm to the base 10 can be calculated with the following identities: [5]
3) Systems of Equations 3.1 Systems of Linear Equations in Three Variables; 3.2 Simultaneous Equations involving One Linear Equation and One Non-Linear Equations; 4) Indices, Surds and Logarithms 4.1 Law of Indices; 4.2 Laws of Surds; 4.3 Laws of Logarithms; 4.4 Applications of Indices, Surds and Logarithms; 5) Progressions 5.1 Arithmetic ...