Path: news.mathworks.com!not-for-mail From: <HIDDEN> Newsgroups: comp.soft-sys.matlab Subject: Re: how to vectorize this loop Date: Tue, 19 Apr 2011 02:04:05 +0000 (UTC) Organization: The MathWorks, Inc. Lines: 29 Message-ID: <ioiqil$42j$1@fred.mathworks.com> References: <ioinh4$f1g$1@fred.mathworks.com> Reply-To: <HIDDEN> NNTP-Posting-Host: www-00-blr.mathworks.com Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: fred.mathworks.com 1303178645 4179 172.30.248.45 (19 Apr 2011 02:04:05 GMT) X-Complaints-To: news@mathworks.com NNTP-Posting-Date: Tue, 19 Apr 2011 02:04:05 +0000 (UTC) X-Newsreader: MATLAB Central Newsreader 1187260 Xref: news.mathworks.com comp.soft-sys.matlab:722623 "Mateusz Gos" <webmaster24@wp.pl> wrote in message <ioinh4$f1g$1@fred.mathworks.com>... > hi, > i would like to write the following loop in form of a vector, which I am guessing is possible (or not?): > > n = 1; > for n = 1:20 > R = mean(measurements(1:n)); > n = n+1; > end > > thanks, > mat - - - - - - - - You should not have the "n = n+1;" line in there. The for-loop with n takes care of advancing n. Also the line "n = 1;" is totally unnecessary since the for-loop will start at n = 1 no matter how you set n in advance. As your code stands at present you are taking twenty different mean operations, the first one the mean of the single number 1, then the mean of the two number 1 and 2, then that of 1, 2, and 3, and so forth. Is that what you had in mind? If so, all but the last one of these means from 1 to 20 have been overwritten because you placed them in the same variable R without indexing it with n. If all you want is the single mean of the numbers from 1 to 20, then do this: R = mean(1:20); If you want the twenty different means, do this: R = zeros(20,1); for n = 1:20 R(n) = mean(1:n); end Roger Stafford