IF statement formatting (related to Runge-Kutta ODE solver)

[certik]

@ivanpribec

it might be easier to just use Scipy or MATLAB. If I’m not mistaken this system is equivalent to the third order equation f’‘’ + f’’ f = (f’)^2 - 1 f′′′+f′′f=(f′)2−1f’‘’ + f’’ f = (f’)^2 - 1 .

Btw, my goal is to make Fortran as easy as MATLAB or SciPy, so that one can do this within Fortran easily.