Fix repeat of same bug

           (b*b*b - b) * Y2[khi]) * (h*h) / 6.0;

#else

        // For a spline with regular grid, we directly calculate the interval X is in.

        int klo = (int)(x / h);

        int klo = (int)(x*(1/h));

        int khi = klo + 1;

        double a = Xs[khi] - x;

        double b = h - a;