FORTRAN 90 - DVERK? - initial condition solver

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Discussion Overview

The discussion revolves around finding a routine in FORTRAN 90 similar to MATLAB's ODE45 for solving initial condition problems in systems of ordinary differential equations (ODEs). Participants explore various methods and resources for implementing these solutions.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant seeks a FORTRAN 90 equivalent to MATLAB's ODE45 for solving initial condition problems.
  • Another participant suggests coding a simple solution using Euler's method, noting its simplicity but lack of precision.
  • A third participant agrees that both Euler's method and fixed step size Runge-Kutta are straightforward but highlights the complexity of adaptive step-size routines like DVERK and ODE45.
  • A later reply provides a reference to RKSUITE as a potential resource for solving ODEs.

Areas of Agreement / Disagreement

Participants generally agree on the simplicity of basic methods like Euler's and fixed step size Runge-Kutta, but recognize the complexity involved in adaptive methods, indicating a lack of consensus on the best approach.

Contextual Notes

Limitations include the assumption that participants are familiar with basic numerical methods and the absence of detailed discussion on the implementation of adaptive step-size routines.

FrogPad
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Hi,

I am new to FORTRAN and am trying to work with a system of ODE's. Does someone know of a routine like DVERK for solving initial condition problems for FORTRAN 90?

In MATLAB I would simply use ODE45. I just need something similar.

Thank you!
 
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Your best bet would be to code your own. Start with a Eulers method, this is very simple though not so precise. A 4th order Runga Kutta routine is also easy to code and is quite accurate. Do a bit of web searching and have a go at it.
 
Yeah both the Euler and the fixed step size Runge-Kutta are simple implementations. The DVERK and ode45 both use adaptive step-size routines, and it gets much more complicated there.
 

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