fwrite a matrix by chunks at a time

hi I am doing some fancier file writing and need to write in a file a matrix, say A=[1:10000]and save it by chunks of 512 datapoints in int16 format. I also need to skip 20bytes in between I am trying fwrite(fid,A,'512*int16',20) but I keep getting a bunch of zeros. ultimately I will use, to read it, a command like fread(fid,512*N,'512*int16=>int16',20); Am I in the correct direction? there is a very small help file for fread.

Answer 1

[Jan]

After some tests I have the impression that:

fwrite(fid, A, '512*int16', 20)

inserts the 20 bytes for skipping before the blocks, while:

fread(fid, 512*N, '512*int16=>int16', 20)

skips the 20 bytes behind the block. Where do you want the skipping bytes? If before the data blocks is wanted, modify the reading like this:

fread(fid, 20, 'int8');  % Skip manually at first
fread(fid, 512*N, '512*int16=>int16', 20)