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A plot of () (left) and its phase line (right). In this case, a and c are both sinks and b is a source. In mathematics , a phase line is a diagram that shows the qualitative behaviour of an autonomous ordinary differential equation in a single variable, d y d x = f ( y ) {\displaystyle {\tfrac {dy}{dx}}=f(y)} .
Stability generally increases to the left of the diagram. [1] Some sink, source or node are equilibrium points . 2-dimensional case refers to Phase plane . In mathematics , an autonomous system or autonomous differential equation is a system of ordinary differential equations which does not explicitly depend on the independent variable .
In applied mathematics, in particular the context of nonlinear system analysis, a phase plane is a visual display of certain characteristics of certain kinds of differential equations; a coordinate plane with axes being the values of the two state variables, say (x, y), or (q, p) etc. (any pair of variables).
In mathematics, the method of characteristics is a technique for solving partial differential equations.Typically, it applies to first-order equations, though in general characteristic curves can also be found for hyperbolic and parabolic partial differential equation.
For example, consider the ordinary differential equation ′ = + The Euler method for solving this equation uses the finite difference quotient (+) ′ to approximate the differential equation by first substituting it for u'(x) then applying a little algebra (multiplying both sides by h, and then adding u(x) to both sides) to get (+) + (() +).
For an arbitrary system of ODEs, a set of solutions (), …, are said to be linearly-independent if: + … + = is satisfied only for = … = =.A second-order differential equation ¨ = (,, ˙) may be converted into a system of first order linear differential equations by defining = ˙, which gives us the first-order system:
With no boundary conditions, the Green's function for the Laplacian (Green's function for the three-variable Laplace equation) is (, ′) = | ′ |. Supposing that the bounding surface goes out to infinity and plugging in this expression for the Green's function finally yields the standard expression for electric potential in terms of electric ...
The defining properties of any LTI system are linearity and time invariance.. Linearity means that the relationship between the input () and the output (), both being regarded as functions, is a linear mapping: If is a constant then the system output to () is (); if ′ is a further input with system output ′ then the output of the system to () + ′ is () + ′ (), this applying for all ...