www.pudn.com > logtools.rar > filtboxnan.m, change:2004-08-13,size:3535b

function y = filtboxnan(x,n) % y = filtboxnan(x,n) % % THIS IS BASICALLY A MOVING AVERAGE OPERATOR % x is the input vector; the no.of pts. of the vector % need not be specified % n is the number of points of the boxcar smoother, % y is the smoothed x, convolved with the % boxcar of n pts. Because the added edges at % the beginning and end are truncated, y will have % the same number of points as x. % T.N.Bishop, CCR, 4/94 % % FILTBOXNAN DIFFERS FROM FILTBOX IN THAT IT HANDLES NaN's % FILTBOX will cause any trace portions containing NaN's to grow larger % by the length of the interpolation function. % FILTBOXNAN avoids this by breaking the % input trace into live segments and interpolating each separately. % The code is taken from Gary's SINCINAN function. % % 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 % first find the live and dead zones ilive=find(~isnan(x)); ind=find(diff(ilive)>1); zone_beg=[ilive(1) ilive(ind+1)]; zone_end=[ilive(ind) ilive(length(ilive))]; nzones=length(zone_beg); % % compute the boxcar function of n points f1 = ones(1,n)/n; % compute the center of the boxcar, assume n is odd nc = fix(n/2) + 1; % compute other stuff npad = n; onepad = ones(1,npad); % % now initialize the output trace with nans, then loop over the zones % and interpolate traces that fall in them y=nan*ones(1,length(x)); for k=1:nzones xzone = x(zone_beg(k):zone_end(k)); % get the input segment in this zone %pad input data with end values xpad = [xzone(1)*onepad xzone xzone(length(xzone))*onepad]; % use Gary's fct from seis.toolbox, to get same no.of % output points as input ypad = convz(xpad,f1,nc,length(xpad),0); %no cosine taper % unpad output data with end values ypad = ypad((npad+1):(length(ypad)-npad)); y(zone_beg(k):zone_end(k))=ypad(1:length(ypad)); end