def _cubic_spline_point(b_coeff, t):
    """
    Internal convenience function for calculating
    a k-dimensional point defined by the supplied
    Bezier coefficients. Finds the point that
    describes the current position along the bezier
    segment for k dimensions.

    params:
        b_coeff => b0...b3: Four k-dimensional Bezier
            coefficients each one is a numpy.array
            of size k by 1, so
            b_coeff is a numpy array of size k by 4
            k is the number of dimensions for each
            coefficient
        t: percentage of time elapsed for this segment
            0 <= int <= 1.0

    returns:
        current position in k dimensions
            numpy.array of size 1 by k
    """
    return (pow((1-t), 3)*b_coeff[:, 0] +
            3*pow((1-t), 2)*t*b_coeff[:, 1] +
            3*(1-t)*pow(t, 2)*b_coeff[:, 2] +
            pow(t, 3)*b_coeff[:, 3]
            )