"""
    ck45()

Returns coefficients rka,rkb,rkc for the 4th order 5-stage low storage Carpenter/Kennedy
Runge Kutta method. Coefficients evolve the residual, solution, and local time, e.g.,

# Example
```julia
res = rk4a[i]*res + dt*rhs # i = RK stage
@. u += rk4b[i]*res
```
"""
function ck45()
    rk4a = [            0.0 ...
    -567301805773.0/1357537059087.0 ...
    -2404267990393.0/2016746695238.0 ...
    -3550918686646.0/2091501179385.0  ...
    -1275806237668.0/842570457699.0];

    rk4b = [ 1432997174477.0/9575080441755.0 ...
    5161836677717.0/13612068292357.0 ...
    1720146321549.0/2090206949498.0  ...
    3134564353537.0/4481467310338.0  ...
    2277821191437.0/14882151754819.0]

    rk4c = [ 0.0  ...
    1432997174477.0/9575080441755.0 ...
    2526269341429.0/6820363962896.0 ...
    2006345519317.0/3224310063776.0 ...
    2802321613138.0/2924317926251.0 ...
    1.0];
    return rk4a, rk4b, rk4c
end

