सामग्री पर जाएँ
The Lumenary
स्नातक (प्रारंभिक)Analysisनियोजित

Ordinary differential equations

First-order equations, linear equations with constant coefficients, linear systems and phase portraits via eigenvalues, existence and uniqueness theorems, and qualitative behaviour.

math.analysis.ordinary-differential-equations

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इस पर आधारित

36 अनिवार्य पूर्वापेक्षाएँ (बिल्कुल नीचे तक)

आप सीखेंगे

  • Solve separable equations, linear first-order equations and constant-coefficient linear equations.
  • Solve linear systems x′ = Ax using eigenvalues and sketch their phase portraits.
  • State the Picard–Lindelöf theorem and give an example of non-uniqueness when its hypotheses fail.

परिभाषा

  • An ordinary differential equation of order n relates an unknown function of one variable to its first n derivatives.
  • An equilibrium of x′ = f(x) is a point where f vanishes.

प्रमेय

  • Picard–Lindelöf: if f is continuous and locally Lipschitz in x, then x′ = f(t, x), x(t₀) = x₀ has a unique solution on some interval around t₀.
  • The solution of x′ = Ax with initial value x(0) is x(t) = e^(tA) x(0).
  • x′ = √|x| with x(0) = 0 has more than one solution, e.g. x ≡ 0 and x(t) = t²/4 for t ≥ 0 (and 0 for t < 0).

आम भ्रांतियाँ

  • Assuming solutions exist for all time; solutions of x′ = x² can blow up in finite time.
  • Thinking every differential equation has a solution in closed form.

आगे ले जाता है

वैकल्पिक खोजें

  • Stochastic processes Adding random noise to differential equations leads to stochastic differential equations.

अधिगम पथ

आगे पढ़ने के लिए

  • Morris W. Hirsch, Stephen Smale and Robert L. Devaney, Differential Equations, Dynamical Systems, and an Introduction to Chaos (2004)
  • Steven H. Strogatz, Nonlinear Dynamics and Chaos (1994)