Solving ODEs with large parameters in Mathematica 9

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SUMMARY

The discussion focuses on solving a specific ordinary differential equation (ODE) using Mathematica 9, particularly with large parameter values for ##k## ranging from ##10^7## to ##10^{12}##. The user reports that while ParametricNDSolve effectively handles small values of ##k##, it struggles significantly with larger values, leading to excessively long computation times. The user seeks alternative methods or workarounds to efficiently solve for the unknown function ##v(x)## under these conditions.

PREREQUISITES
  • Understanding of ordinary differential equations (ODEs)
  • Familiarity with Mathematica 9 and its functions, particularly ParametricNDSolve
  • Knowledge of interpolation methods in Mathematica
  • Basic grasp of numerical methods for solving differential equations
NEXT STEPS
  • Explore alternative numerical methods for ODEs, such as NDSolve in Mathematica
  • Research techniques for parameter continuation in differential equations
  • Investigate the use of adaptive step size control in Mathematica
  • Learn about preconditioning techniques to improve convergence for large parameter values
USEFUL FOR

Mathematicians, engineers, and researchers working with differential equations, particularly those using Mathematica for numerical solutions involving large parameters.

WannabeNewton
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I have an ODE ##e^{2x}H(Hv'(x) + H'v' + Hv'') + (k^2 - 2e^{2x}H^2(1 + \frac{H'}{2H}))v = 0## where ##H(x)## is a known function that Mathematica has stored as an interpolation from a previous ODE and ##v(x)## is the unknown function to be solved for. ##k## is the adjustable parameter. Using ParametricNDSolve, Mathematica has no problem solving for an interpolation of ##v## if ##k## is very small e.g. on the order of ##10^{-3}## or even on the order of unity. But I have to solve for ##v## using values of ##k## that are of the order ##10^7## to ##10^{12}##. Right now I'm running ParametricNDSolve for ##k \sim 10^7## and it is taking ages to solve for ##v##. In fact I don't know if it actually will eventually solve for ##v## in a reasonable amount of time. If it doesn't solve it in a reasonable amount of time then I have no hope of ParametricNDSolve solving it in uniform steps between ##k \sim 10^7## and ##k \sim 10^{12}##. Is there a reasonable way to work around this?
 
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