explain data(i,1:381)=wave(i,1:381)+normrnd(0,ppamp*var,1,381); in matlab

This line of code is performing matrix addition between two matrices "wave" and "normrnd" and then storing it in another matrix called "data".

The "wave" matrix has the same number of rows and 381 columns as that of the "data" matrix. The values of the first row of the "wave" matrix are being added with a row vector of length 381 which is obtained by generating pseudo-random numbers (normrnd(0,ppamp*var,1,381)), with mean 0 and variance ppamp*var.

The resulting row vector and the first row of the "wave" matrix are being added element-wise and stored in the first row of the "data" matrix. This process is repeated for all the rows of the "wave" matrix and the "data" matrix is completely filled out.

Overall, this line of code is used to simulate noisy data in which the random noise is added to the original data obtained from the "wave" matrix.