Lothar Schmidt <vapooroop@gmx.net> wrote in message
<g6cerv$uc0$01$1@news.tonline.com>...
> Dave Brackett schrieb:
> > I have been using a peak detection m file from
> > http://www.billauer.co.il/peakdet.html. The code is
shown below.
> >
> > Does anyone know if its possible to vectorise this function
> > as it currently uses for loops? and if it is, could you show
> > me how please? thanks. more info can be found at the
above link.
> >
> >
> >
> > function [maxtab, mintab]=peakdet(v, delta)
> > %PEAKDET Detect peaks in a vector
> > % [MAXTAB, MINTAB] = PEAKDET(V, DELTA) finds the
local
> > % maxima and minima ("peaks") in the vector V.
> > % A point is considered a maximum peak if it has the
> > maximal
> > % value, and was preceded (to the left) by a value
> > lower by
> > % DELTA. MAXTAB and MINTAB consists of two columns.
> > Column 1
> > % contains indices in V, and column 2 the found
values.
> >
> > % Eli Billauer, 3.4.05 (Explicitly not copyrighted).
> > % This function is released to the public domain; Any use is
> > allowed.
> >
> > maxtab = [];
> > mintab = [];
> >
> > v = v(:); % Just in case this wasn't a proper vector
> >
> > if (length(delta(:)))>1
> > error('Input argument DELTA must be a scalar');
> > end
> >
> > if delta <= 0
> > error('Input argument DELTA must be positive');
> > end
> >
> > mn = Inf; mx = Inf;
> > mnpos = NaN; mxpos = NaN;
> >
> > lookformax = 1;
> >
> > for i=1:length(v)
> > this = v(i);
> > if this > mx, mx = this; mxpos = i; end
> > if this < mn, mn = this; mnpos = i; end
> >
> > if lookformax
> > if this < mxdelta
> > maxtab = [maxtab ; mxpos mx];
> > mn = this; mnpos = i;
> > lookformax = 0;
> > end
> > else
> > if this > mn+delta
> > mintab = [mintab ; mnpos mn];
> > mx = this; mxpos = i;
> > lookformax = 1;
> > end
> > end
> > end
> >
> >
>
> index=2:length(v)1;
> MAX_pos=find(v(i1)+delta<v(i) & v(i+1)+delta<v(i))+1;
>
> for finding the minima you'll shurely find a similar
solution :)
>
> Lothar
>
>
so those 2 lines do the same as most of that code? nice.
I am keen to get it to handle an arbitrary number of vectors
in matrix form as currently it can only handle single
vectors. As such I have been looping the whole function for
each vector which is slow. could you show me how to adapt
your vectorised version to allow this please? thanks.
