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

    if (k < 0)
    {
        return Linear(v[0], v[1], f);
    }
    else if (k > 1)
    {
        return Linear(v[m], v[m - 1], m - f);
    }
    else
    {
        return Linear(v[i], v[(i + 1 > m) ? m : i + 1], f - i);
    }
}
A linear interpolation method.

@function Phaser.Math.Interpolation.Linear
@since 3.0.0
@see {@link https://en.wikipedia.org/wiki/Linear_interpolation}

@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.