DE Solver

This code uses Runge Kutta algorithm and shooting method for solving the Differential Equation

ode/ode_coupled_rk.f95

This code is used for solving coupled and second order non-eigen ODE's using 4th order Runge Kutta method. For the latter, change ode2 function to look like z1=y.

ode/ode_evp_rk_ord1.f95

This code is used for solving first order eigen value ODE's using 4th order Runge Kutta method. However, you are required to put two estimates to get the eigen values.

ode/ode_evp_rk_ord2.f95

This code is used for solving second order eigen value ODE's using 4th order Runge Kutta method. However, you are required to put two estimates to get the eigen values. Please keep an eye on normalization while solving.

ode/ode_ord2_ev_det.f95

This code is used to determine the possible eigen values of a second order ODE. It basically plots y_exp-y_calc vs different values of the eigen value parameter (m in this code) and the zeros of this function are the eigen values. This code is a half-finished one and can be considered as an extension of ode/ode_evp_rk_ode2.f95.

ode/ode_ord2_all_eval_range.f95

This code is used to determine all the eigen values and eigen vectors in a given range for a second order ODE. There are options for normalization of the eigen vector, which is generally done in case of solving quantum mechanical systems. However, one has to be a bit careful while setting the stepsize,i.e. it should not exceed the least difference between two eigen values.

COMPILATION AND USAGE:

These codes have been complied using gfortran 5.4.0 and tested in Linux Mint 18.1. It is expected that the codes will compile in the same or higher version of gfortran. Since there are quite a few interactions with files, the user is requested to download and complie the code rather than using any online compiler.