event_hyp.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 amat=event_hyp(amat,t,x,tnot,xnot,v,amp,flag,aper)

% amat=event_hyp(amat,t,x,tnot,xnot,v,amp,flag,aper)
%
% EVENT_HYP inserts a hyperbolic event in a matrix.
%
% amat ... the matrix of size nrows by ncols
% t ... vector of length nrows giving the matrix t coordinates
% x ... vector of length ncols giving the matrix x coordinates
% tnot ... t coordinate of the hyperbola apex
% xnot ... x coordinate of the hyperbola apex
% v ... velocity of hyperbola
% amp ... amplitude at the apex
% flag ... determines amplitude decay on hyperbola
%		0 -> no decay
%		1 -> decay as to/tx
%		2 -> decay as to/(tx^2)
% ******** default is 1 ********
% aper ... truncate hyperbola beyond this aperture
% ******** default is no truncation ********
%
% G.F. Margrave, CREWES Project, University of Calgary, 1996
%
% 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

%
if(nargin<8)
	flag=1;
end
if( nargin < 9 )
	aper = inf;
end

%loop over columns
[nsamp,nc]=size(amat);

dt=t(2)-t(1);
tmin=t(1);
for k=1:nc
	xoff=x(k)-xnot;
	if(abs(xoff) < aper)
		tk = sqrt(tnot^2+(xoff/v)^2);
		a=amp;
		if(flag==1)
			a = tnot*a/tk;
		elseif(flag==2)
			a = tnot*a/(tk*tk);
		end
		ik=(tk-tmin)/dt+1;
		if( between(1,nsamp,ik) )
			ik1=floor(ik);
			ik2=ceil(ik);
			if(ik1==ik2)
				amat(ik1,k)=amat(ik1,k)+a;
			else
				amat(ik1,k)=amat(ik1,k)+a*(ik-ik2)/(ik1-ik2);
				amat(ik2,k)=amat(ik2,k)+a*(ik-ik1)/(ik2-ik1);
			end
		end
	end
end