function header=header(FID,ns,k)%HEADER: Returns the complete trace header of trace k.%%   The trace complete trace header of trace k is loaded%   in a structure called header. This fucntion is used %   by readsegy.m%%   header = header(FID,ns,k);%%   IN   FID: file identifier number (set by fopen)%        ns: numer of samples per trace (can be obatained using%            extract.m)%        k: trace number you want to retrieve the header from %%   Example: header = header(FID,1024,10) gets the complete header%                     of the trace 10 in the file FID (already opened with %                     FID=fopen(...)). The trace has 1024 samples. %%%  M.D.Sacchi, July 1997, Dept. of Physics, UofA.%%  sacchi@phys.ualberta.ca%   offset = (240+ns*4)*(k-1);   status=fseek(FID,offset,'bof');   %跳轉到要進行字提取的道的前面   header.tracl=fread(FID,1,'int');       header.tracr=fread(FID,1,'int');        header.fldr=fread(FID,1,'int');        header.tracf=fread(FID,1,'int');    header.ep=fread(FID,1,'int');          header.cdp=fread(FID,1,'int');        header.cdpt=fread(FID,1,'int');       header.trid=fread(FID,1,'short');    header.nva=fread(FID,1,'short');       header.nhs=fread(FID,1,'short');      header.duse=fread(FID,1,'short');      header.offset=fread(FID,1,'int');      header.gelev=fread(FID,1,'int');     header.selev=fread(FID,1,'int');       header.sdepth=fread(FID,1,'int');      header.gdel=fread(FID,1,'int');        header.sdel=fread(FID,1,'int');        header.swdep=fread(FID,1,'int');      header.gwdep=fread(FID,1,'int');    header.scalel=fread(FID,1,'short');    header.scalco=fread(FID,1,'short');    header.sx=fread(FID,1,'int');          header.sy=fread(FID,1,'int');          header.gx=fread(FID,1,'int');          header.gy=fread(FID,1,'int');          header.counit=fread(FID,1,'short');    header.wevel=fread(FID,1,'short');     header.swevel=fread(FID,1,'short');    header.sut=fread(FID,1,'short');       header.gut=fread(FID,1,'short');       header.sstat=fread(FID,1,'short');     header.gstat=fread(FID,1,'short');     header.tstat=fread(FID,1,'short');     header.laga=fread(FID,1,'short');      header.lagb=fread(FID,1,'short');      header.delrt=fread(FID,1,'short');     header.muts=fread(FID,1,'short');      header.mute=fread(FID,1,'short');      header.ns=fread(FID,1,'unsigned short');     header.dt=fread(FID,1,'unsigned short');     header.gain=fread(FID,1,'short');      header.igc=fread(FID,1,'short');       header.igi=fread(FID,1,'short');      header.corr=fread(FID,1,'short');      header.sfs=fread(FID,1,'short');       header.sfe=fread(FID,1,'short');       header.slen=fread(FID,1,'short');     header.styp=fread(FID,1,'short');     header.stas=fread(FID,1,'short');      header.stae=fread(FID,1,'short');     header.tatyp=fread(FID,1,'short');     header.afilf=fread(FID,1,'short');     header.afils=fread(FID,1,'short');     header.nofilf=fread(FID,1,'short');    header.nofils=fread(FID,1,'short');    header.lcf=fread(FID,1,'short');       header.hcf=fread(FID,1,'short');      header.lcs=fread(FID,1,'short');      header.hcs=fread(FID,1,'short');      header.year=fread(FID,1,'short');      header.day=fread(FID,1,'short');       header.hour=fread(FID,1,'short');      header.minute=fread(FID,1,'short');    header.sec=fread(FID,1,'short');       header.timbas=fread(FID,1,'short');    header.trwf=fread(FID,1,'short');      header.grnors=fread(FID,1,'short');    header.grnofr=fread(FID,1,'short');    header.grnlof=fread(FID,1,'short');    header.gaps=fread(FID,1,'short');      header.otrav=fread(FID,1,'short');     header.d1=fread(FID,1,'float');        header.f1=fread(FID,1,'float');        header.d2=fread(FID,1,'float');        header.f2=fread(FID,1,'float');        header.ungpow=fread(FID,1,'float');    header.unscale=fread(FID,1,'float');   header.ntr=fread(FID,1,'int');        header.mark=fread(FID,1,'short');     header.unass=fread(FID,15,'short');