利用C语言拟合的自由曲线，将12个点以x坐标从小到大，将这12个点以3个点为一组，以二次函数曲线为一来拟合自由曲线。-C language of freedom curve fitting, 12 points to x coordinates from small to large, these 12 points to three points for a group to a quadratic function of a curve to curve fitting freedom.