Calculus of variations problem and differential equation initial conditions

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SUMMARY

The discussion focuses on solving a calculus of variations problem involving the integral of (1 + yy')² dx from 0 to 1 and interpreting the limits of integration as initial conditions for the corresponding Euler-Lagrange differential equation. The participants confirm that Laplace transforms can be utilized to solve differential equations even when initial conditions for y' are unknown, by substituting a general function or constant in place of y'. This method has been successfully applied to Laplace's equation, demonstrating its effectiveness in finding solutions under specific conditions.

PREREQUISITES
  • Understanding of calculus of variations and the Euler-Lagrange equation
  • Familiarity with Laplace transforms and their application in differential equations
  • Knowledge of initial conditions in the context of differential equations
  • Basic proficiency in integral calculus
NEXT STEPS
  • Study the derivation and applications of the Euler-Lagrange equation in calculus of variations
  • Learn how to apply Laplace transforms to solve differential equations with missing initial conditions
  • Explore methods for minimizing integrals in calculus of variations problems
  • Investigate the implications of arbitrary constants in differential equations and their solutions
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Mathematicians, physics students, and engineers dealing with calculus of variations and differential equations, particularly those interested in optimization and solution techniques for complex integrals.

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Calculus of variations problem. I want to make stationary the integral of (1+yy')^2 dx from 0 to 1. I know what the Euler-Lagrange differential equation turns out to be, but how do I interpret the limits of integration as initial conditions for the diff eq?

also, can i use laplace transforms to solve differential equations if I know a few initial conditions for y, but no initial conditions for y'?

Thanks!
 
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Okay, I will answer the second question first and then suggestions for the first.

The answer to this one is take a dufferential equation which you know the solution of and swap the intial condition for y' for something else and take laplace transforms of your equation and leave a general function (or possibly constant) in it's place and then go through as normal and see if you can't find out the constant using the other condition you have. I solve Lapalces's equation this way and it worked perfectly fine.

For the first question, can you solve te equation you get with some arbitrary constants in? If so plug this back into the integral, do the integral and then minimise the results in the usual way.
 

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