在MATLAB中，已知两组数据x y，怎样通过线性拟合，使得到的三次拟合多项式经过指定的点呢？例如原点

使用cftool工具箱
普通三次拟合
Linear model Poly3:
f(x) = p1*x^3 + p2*x^2 + p3*x + p4
Coefficients (with 95% confidence bounds):
p1 = 0.006245 (0.0038, 0.008689)
p2 = -0.2037 (-0.2668, -0.1406)
p3 = 2.182 (1.713, 2.651)
p4 = 2.572 (1.623, 3.521)

Goodness of fit:
SSE: 1.37
R-square: 0.972
Adjusted R-square: 0.965
RMSE: 0.3379

过原点的拟合
General model:
f(x) = x*(p1*x^2 + p2*x + p3)
Coefficients (with 95% confidence bounds):
p1 = 0.0112 (0.008154, 0.01426)
p2 = -0.344 (-0.4119, -0.2761)
p3 = 3.342 (2.981, 3.702)

Goodness of fit:
SSE: 5.35
R-square: 0.8906
Adjusted R-square: 0.8737
RMSE: 0.6415