min=x1*log(x1)+x2*log(x2)+x3*log(x3)；约束是x1+x2+x3=1; 为什么在lingo里报错.请大侠指导

min=x1*log(x1)+x2*log(x2)+x3*log(x3)；约束是x1+x2+x3=1; 为什么在lingo里报错.请大侠指导

min=x1*@log(x1)+x2*@log(x2)+x3*@log(x3);
x1+x2+x3=1;