sigfig.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 [xx,xp,e]=sigfig(x,n)

% [xx,xp,e]=sigfig(x,n)
%
% SIGFIG returns x rounded to n significant figures
% (works for vectors)
% 
% xx ... x rounded to n sig figures
% xp and e ... xx==xp*10^e where 0<abs(xp)<1000
% 
% 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 
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%
% END TERMS OF USE LICENSE


xx=zeros(size(x));
xp=xx;
e=xx;

ind=find(x~=0.);

xl=log10(x(ind));

ee= fix(xl);

if(xl<0)
	tmp=10.^(xl-ee+n);
	xx(ind)=round(tmp).*10.^(ee-n);
	xl=log10(x(ind));
	e(ind)=fix(xl);
	xp(ind)=10.^(xl-ee);
else
	tmp=10.^(xl-ee+n-1);
	xx(ind)=round(tmp).*10.^(ee-n+1);
	xl=log10(x(ind));
	e(ind)=fix(xl);
	xp(ind)=10.^(xl-ee);
end