Calculus of Variations Dependent variables and constraints

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SUMMARY

The discussion focuses on the application of the Euler-Lagrange equations in the context of the calculus of variations, specifically for a function f(x, x', y, y', t) subject to a constraint g(x, x', y, y', t). Participants clarify that two Euler-Lagrange equations are necessary for the dependent variables x and y. The question arises whether a single constant A can be used for the constraint term in both equations or if different constants are required for each equation. Explicit definitions of the constraint are also requested to establish the set of generalized coordinates.

PREREQUISITES
  • Understanding of the Euler-Lagrange equations
  • Familiarity with the calculus of variations
  • Knowledge of dependent and independent variables in mathematical functions
  • Basic concepts of constraints in optimization problems
NEXT STEPS
  • Study the derivation and applications of the Euler-Lagrange equations
  • Explore advanced topics in the calculus of variations, such as Hamiltonian mechanics
  • Investigate the role of constraints in optimization, focusing on Lagrange multipliers
  • Learn about generalized coordinates and their significance in physics and engineering
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Mathematicians, physicists, and engineers involved in optimization problems, particularly those utilizing the calculus of variations and the Euler-Lagrange framework.

shedrick94
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If we have a function:

\begin{equation} f(x,x',y,y',t) \end{equation} and we are trying to minimise this subject to a constraint of
\begin{equation} g(x,x',y,y',t) \end{equation}

Would we simply have a set of two euler lagrange equations for each dependent variable, here we have x and y.

Would we insert f(x,x',y,y',t)-Ag(x,x',y,y',t) into both equations, where A is a constant? Or would each equation require a different constant in front of the constraint term g(x,x',y,y',t)??
 
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shedrick94 said:
and we are trying to minimise this subject to a constraint of.
g(x,x′,y,y′,t)​
(2)(2)g(x,x′,y,y′,t)\begin{equation} g(x,x',y,y',t) \end{equation}

Would we simply have a set of two euler lagrange equations for each dependent variable, here we have x and y.

pl. give explicit eq of constraint -that will define the set of generalized coordinates.
 

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