不会是把整个math库全编译进去了吧
使用exp
   U16 Ch0,Ch1,lux;
    Ch0=AdcDecode(a0);
    Ch1=AdcDecode(a1);
    lux=(U16)(5*(Ch0-Ch1)*0.39*exp(-0.181*Ch1*Ch1/(Ch0-Ch1)/(Ch0-Ch1)));

Program space        used   F68h (  3944) of  1000h words   ( 96.3%)

不用exp
    U16 Ch0,Ch1,lux;
    Ch0=AdcDecode(a0);
    Ch1=AdcDecode(a1);
    lux=(U16)(5*(Ch0-Ch1)*0.39*(-0.181*Ch1*Ch1/(Ch0-Ch1)/(Ch0-Ch1)));
Program space        used   B4Ah (  2890) of  1000h words   ( 70.6%)