function [bits_alloc,energy_alloc] = chow_algo(SNR,num_subc,M)

for i = 1:num_subc
%假設每個子信道都是平坦衰落信道
%初始化每個子信道的比特數 
    tempbits        =log2(1+abs(SNR(i)));
    roundtempbits   =round(tempbits);       %取整
    
    if(roundtempbits>8)                     %將比特數限制在2~15之間
        roundtempbits = 8;
    end
    
    if(mod(roundtempbits,2) ==1&roundtempbits~=1)
        roundtempbits =roundtempbits -1;
    end
    
    if roundtempbits>0                      %計算每個子信道的功率
        energy_alloc(i)=(2^roundtempbits-1)/SNR(i);
    else
        energy_alloc(i) = 0;
    end
    bits_alloc(i) = roundtempbits;          %更新每個子信道的比特數
end