可以进行曲线回归拟合算法的四参数算法。函数为 y = (a-d)/(1+(x/c)^b) +d . ec50.m 为其主要函数-Can curve fitting algorithm of the four-parameter algorithm. Function y = (ad)/(1+ (X/c) ^ b)+ D. Ec50.m its main function

利用贝叶斯原理估计混合logit模型的参数，包括四元数的各种计算,利用最小二乘算法实现对三维平面的拟合。- Bayesian parameter estimation principle mixed logit model, Including quaternion various calculations, Least-squares algorithm to fit a three-dimensional plane.

四参数拟合算法的实现，对现实中的拟合效果不错！(Implementation of four parameter fitting algorithm)