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