64QAM code help in (ipHat)

i NEED TO KNOW WHAT IS MEANT BY "ipHat" in line 5 and 7

CODE: 1.k = sqrt(1/((2/3)*(M-1))); %% normalizing factor

2.m = [1:sqrt(M)/2]; %% alphabets 3.alphaMqam = [-(2*m-1) 2*m-1];

4.Es_N0_dB = [0:30]; %% multiple Es/N0 values

5.ipHat = zeros(1,N); %% init

6.for ii = 1:length(Es_N0_dB)

7.ip = randsrc(1,N,alphaMqam) + j*randsrc(1,N,alphaMqam); 8.s = k*ip; %% normalization of energy to 1 9.n = 1/sqrt(2)*[randn(1,N) + j*randn(1,N)]; % white guassian noise, 0dB variance