old code:
	coeffsU[0] = (1 - u) * (1 - u) * (1 - u);
	coeffsU[1] = 3 * u * (1 - u) * (1 - u);
	coeffsU[2] = 3 * u * u * (1 - u);
	coeffsU[3] = u * u * u;

new code:
	if (u != 1)
	{
		u[0] = pow(1 - u, GRID_WIDTH - 1);
		i = 1;
		
		if (i < 4)
			u[i] = u[i - 1] * u / (1 - u);
			u[i] *= (float)(4 - i) / i;
			i++;	// i == 2
		
		if (i < 4)
			u[i] = u[i - 1] * u / (1 - u);
			u[i] *= (float)(4 - i) / i;
			i++;	// i == 3
		
		if (i < 4)
			u[i] = u[i - 1] * u / (1 - u);
			u[i] *= (float)(4 - i) / i;
			i++;	// i == 4
		
		if (i < 4)	// won't enter
	}

	else
	{
		i = 0;
		
		if (i < 4 - 1)
			u[i] = 0
			i++;	// i == 1
		
		if (i < 4 - 1)
			u[i] = 0
			i++;	// i == 2
		
		if (i < 4 - 1)
			u[i] = 0
			i++;	// i == 3
		
		if (i < 4 - 1) // won't enter
		
		u[i] = i;
	}