readwavelet.m

基于matlab的反演程序,用于地球物理勘探中射线追踪及偏移成像程序.

function [w,t,wname]=readwavelet(filename)

% [w,t,wname]=readwavelet(filename)
%
% Reads a wavelet from disk in either 2 column headerless format or
% in GMA format
% Any kind of a read failure (no file, empty file etc) is flagged by 
% returning w=-1
%
% NOTE: It is illegal for you to use this software for a purpose other
% than non-profit education or research UNLESS you are employed by a CREWES
% Project sponsor. By using this software, you are agreeing to the terms
% detailed in this software's Matlab source file.
 
% BEGIN TERMS OF USE LICENSE
%
% This SOFTWARE is maintained by the CREWES Project at the Department
% of Geology and Geophysics of the University of Calgary, Calgary,
% Alberta, Canada.  The copyright and ownership is jointly held by 
% its author (identified above) and the CREWES Project.  The CREWES 
% project may be contacted via email at:  [e-mail]
% 
% The term 'SOFTWARE' refers to the Matlab source code, translations to
% any other computer language, or object code
%
% Terms of use of this SOFTWARE
%
% 1) Use of this SOFTWARE by any for-profit commercial organization is
%    expressly forbidden unless said organization is a CREWES Project
%    Sponsor.
%
% 2) A CREWES Project sponsor may use this SOFTWARE under the terms of the 
%    CREWES Project Sponsorship agreement.
%
% 3) A student or employee of a non-profit educational institution may 
%    use this SOFTWARE subject to the following terms and conditions:
%    - this SOFTWARE is for teaching or research purposes only.
%    - this SOFTWARE may be distributed to other students or researchers 
%      provided that these license terms are included.
%    - reselling the SOFTWARE, or including it or any portion of it, in any
%      software that will be resold is expressly forbidden.
%    - transfering the SOFTWARE in any form to a commercial firm or any 
%      other for-profit organization is expressly forbidden.
%
% END TERMS OF USE LICENSE

	w=-1;
	t=-1;
    wname='';

%open the file
fid=fopen(filename);
if(fid==-1)
	return;
end

%read the first line
rec=fgetl(fid);
if( ~isempty(rec) )
	if( rec==-1 )
		return;
	end
end
%test for gma file
gma=0;
if( length( rec) > 8 )
	if( strcmp(rec(2:8),'WAVELET') )
		gma=1;
	end
end

% read a gma file
if(gma)
	%form a name from record 1
	%wname=sscanf(rec,'%*s %*s %s %*f %*s %*f %*s %*f %*s %*s %*s');
	wname=deblank(rec(12:40));
	ind=find(abs(wname==32));
	if(~isempty(ind))
		wname=wname(1:ind(1)-1);
	end

	wname=[wname '_logm'];

	%next record
	rec=fgetl(fid);

	%read sample rate, start & end times
	dt=sscanf(rec,'%*s %*s %*s %f %*s %*s %*s %*f %*s %*s %*s %*f %*s');
 tmin=sscanf(rec,'%*s %*s %*s %*f %*s %*s %*s %f %*s %*s %*s %*f %*s');
 tmax=sscanf(rec,'%*s %*s %*s %*f %*s %*s %*s %*f %*s %*s %*s %f %*s');

 t=tmin:dt:tmax;
 t=t'/1000;

 %skip two lines
 rec=fgetl(fid);
 rec=fgetl(fid);

 %read in the amplitudes
 w=fscanf(fid,'%g',inf);

 return;
else
 %we assume it contains just two columns of numbers
 frewind(fid);
 dat=fscanf(fid,'%g %g',[2,inf]);
 if(isempty(dat))
		return;
	end
 t=dat(1,:)';
 w=dat(2,:)';
 wname='nameless';

 return;
end