www.pudn.com > geometric.rar > arclen2xy.m, change:2004-08-13,size:2528b

function [xnot,ynot]=arclen2xy(x,y,a)  % [xnot,ynot]=arclen2xy(x,y,a) % % Given a piecewise linear curve whose nodes are described by the vectors % x & y, ARCLEN2XY computes the (x,y) coordinates of the points whose % arclength (or inline distance) from (x(1),y(1)) is given by the vector a. % If the arclength is too large (or negative) then NaN is returned. % % 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   anodes=xy2arclen(x,y); anodes(length(anodes))=anodes(length(anodes))+5*eps;  n=length(a); xnot=nan*ones(size(a)); ynot=nan*ones(size(a));  for k=1:n  	ind=surround(anodes,a(k)); 	if(~isempty(ind)) 		ind=ind(1);% make sure we take the first one 		if( ind>0 ) 			factor=(a(k)-anodes(ind))/(anodes(ind+1)-anodes(ind)); 			xnot(k)=x(ind)+factor*(x(ind+1)-x(ind)); 			ynot(k)=y(ind)+factor*(y(ind+1)-y(ind)); 		end 	end 	 end