www.pudn.com > geometric.rar > closestnode.m, change:2004-08-13,size:2862b


function inode=closestnode(x,y,xnot,ynot)  % inode=closestnode(x,y,xnot,ynot) %  % Given a piecewise linear curve whose nodes are defined by the vectors x & y % CLOSESTNODE returns the index of the node on the curve which is closest to % the point (xnot,ynot) % % G.F. Margrave, December 1993 % % 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:  crewesinfo@crewes.org %  % 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  it=[]; n=length(x);  % test for equality ind= find(x==xnot); if(~isempty(ind)) 	ind2=find(y(ind)==ynot); 	if(~isempty(ind2)) 			inode=ind(ind2); 			return; 	end end  % find the points which bracket xnot,ynot indx = surround(x,xnot); indy = surround(y,ynot);  for k=1:length(indx) 	if isempty(indy)  		it=find(isempty(indx(k))); 	else 		it=find(indx(k)==indy); 	end 	if ~isempty(it) 		itest=indx(k); 		break; 	end end  if(isempty(it)) 	% if no points bracket (xnot,ynot) then it is way exterior to the curve 	% we have no choice but to compute the distances to the various nodes and find  	% the minimum 	d=sqrt( (x-xnot).^2 + (y-ynot).^2 ); 	[d,ind]=sort(d); 	inode=ind(1); 	return; else 	itest=[itest itest+1]; 	d=sqrt( (x(itest)-xnot).^2 + (y(itest)-ynot).^2 ); 	ind=find(d==min(d)); 	inode=itest(ind(1));% just in case we get two minima 	return; end