thank you Alex for your respon, Normal 0 false false false EN-US JA AR-SA MicrosoftInternetExplorer4 How about this vegetation index GEMI: Global Environmental Monitoring Index? How can write this expression? Normal 0 false false false EN-US JA AR-SA MicrosoftInternetExplorer4 How can write this expression? Just I write so many times this expression; 2*((float(B4)^2float(B3)^2)+(1.5*float(B4)+0.5*float(B3)/(float(B4)+float(B3)+0.5)*(1-0.25*(2*(float(B4)^2 float(B3)^2)+(1.5*float(B4)+0.5*float(B3))/(float(B4)+float(B3)+0.5)))-(float(B3)-0.125)/(1-float(B3)) thank you