tor, 02 07 2009 kl. 22:48 +0200, skrev Autiwa:
> Ok, I think it's good now :)
Thanks. Since nobody has commented, I assume people think your stuff is
good :-)
I've (hopefully) made the documentation somewhat more clear, and changed
the coding-style a bit. Could you check that I haven't broken anything?
I'm attaching the code.
By the way, what is your full name? I think you should be given credit
for the code.
Thanks
Søren
## -*- texinfo -*-
## @deftypefn {Function File} {} fwhm (@var{f})
## @deftypefnx{Function File} {} fwhm (@var{x}, @var{f})
## Return the full width at half maximum if a given signal.
##
## The full width at half maximum is an expression of the extent of a signal,
## defined as the difference between the two extremal points of the signal where
## it equals half of its maximum value.
##
## The signal is given by the vector @var{f} with optional @math{x}-values
## @var{x}. If the latter is not given, it defaults to the indexes of @var{f}.
##
## If the full width at half maximum is not defined, an error is raised.
## @seealso{std}
## @end deftypefn
## This program is public domain.
function retval = fwhm (x, f)
## Check input
if (nargin == 0)
error ("fwhm: not enough input arguments");
elseif (nargin == 1)
f = x;
x = 1:length (f);
endif
if (numel (x) != numel (f))
error ("fwhm: number of elements does not match");
endif
## Locate maximum
fmax = max (f);
f_renorm = f - 0.5 * fmax;
ind = find (f_renorm(1:end-1) .* f_renorm (2:end) <= 0);
## If the product is negative, this means that the "half-maximum" is between
## theses two values
if (length (ind) == 2)
## We make a linear regression between the two values to get a more precise
## estimation of the fwhm.
x1 = (0.5 * fmax - f (ind (1) + 1)) * (x (ind (1) + 1) - x (ind (1))) ...
/ (f (ind (1) + 1) - f (ind (1))) + x (ind (1) + 1);
x2 = (0.5 * fmax - f (ind (end) + 1)) * (x (ind (end) + 1) - x (ind (end))) ...
/ (f (ind (end) + 1) - f (ind (end))) + x (ind (end) + 1);
retval = x2 - x1;
else
error ("fwhm: full width at half maximum is not defined.");
endif
endfunction
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