function Get_a_b(fNDVI,fLST);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%功能描述：根据植被指数NDVI和地表温度计算相应的干边与湿边参数   %%
%%算法描述：NDVI从0到1，以0.01+0.02*n (n=1,2,...,49)为中心，取             %%
%%0.02宽度的区间中LST的最大值和最小值，分别与其对应的NDVI值组成  %%
%%点对（如: (NDVI, LSTmax])，最后采用最小二乘线性拟合方式将点对        %%
%%拟合，形成湿边和干边                                                                                      %%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
NDVI=imread(fNDVI);
LST=imread(fLST);

for n=1:49
   I=find(0.02*n<NDVI & NDVI<0.02+0.02*n);
   LSTmax= max(LST(I));
   LSTmin= min(LST(I));
   NDVI_LSTmax(n,:)=[0.01+0.02*n LSTmax];
   NDVI_LSTmin(n,:)=[0.01+0.02*n LSTmin];
end
Xmax=NDVI_LSTmax(:,1);
Ymax=NDVI_LSTmax(:,2);
Pabmax=ployfit(Xmax,Ymax,2)

Xmin=NDVI_LSTmin(:,1);
Ymin=NDVI_LSTmin(:,2);
Pabmin=ployfit(Xmin,Ymin,2)