CatmullRomInterpolation = function (v, k)
{
    var m = v.length - 1;
    var f = m * k;
    var i = Math.floor(f);

    if (v[0] === v[m])
    {
        if (k < 0)
        {
            i = Math.floor(f = m * (1 + k));
        }

        return CatmullRom(f - i, v[(i - 1 + m) % m], v[i], v[(i + 1) % m], v[(i + 2) % m]);
    }
    else
    {
        if (k < 0)
        {
            return v[0] - (CatmullRom(-f, v[0], v[0], v[1], v[1]) - v[0]);
        }

        if (k > 1)
        {
            return v[m] - (CatmullRom(f - m, v[m], v[m], v[m - 1], v[m - 1]) - v[m]);
        }

        return CatmullRom(f - i, v[i ? i - 1 : 0], v[i], v[m < i + 1 ? m : i + 1], v[m < i + 2 ? m : i + 2]);
    }
}
A Catmull-Rom interpolation method.

@function Phaser.Math.Interpolation.CatmullRom
@since 3.0.0

@param {number[]} v - The input array of values to interpolate between.
@param {number} k - The percentage of interpolation, between 0 and 1.

@return {number} The interpolated value.