ppval1.m

算荧光衰减时间或者寿命的软件.matlab语言编写.

function v=ppval1(ppfun,xx)
%PPVAL1 Fast 1-D Piecewise Polynomial Evaluation.
% PPVAL1(PP,XI) evaluates the piecewise polynomial PP at the points
% specified in XI.
% This function is equivalent to PPVAL in MATLAB, but faster since it is
% restricted to 1-D polynomials and it uses HISTC to find the local
% coordinates of each point in XI. For scalar XI, it is even faster.
%
% This function is used by PPCREATE, PPINTEGRAL, PPGRADIENT

% D.C. Hanselman, University of Maine, Orono, ME 04469
% [e-mail]
% Mastering MATLAB 7
% 2005-10-17

if isa(ppfun,'function_handle') % accept function input to be nice
   pp=ppfun('pp');
else
   pp=ppfun;
end
if ~isstruct(pp) || ~isfield(pp,'form') ...
   || ~strcmp(pp.form,'pp') || (pp.dim~=1);
   error('Input Does Not Contain a 1-D Piecewise Polynomial.')
end
if numel(xx)==1   % scalar input
   idx=find(xx>=pp.breaks);
   if isempty(idx)               % extrapolate if necessary
      idx=1;
   elseif idx(end)>pp.pieces
      idx=pp.pieces;
   end
   xs=xx-pp.breaks(idx(end));    % local coordinates
   c=pp.coefs(idx(end),:);       % local polynomial
   if pp.order==4                % quick eval for cubic spline
      v=((c(1)*xs + c(2))*xs + c(3))*xs +c(4);
   else
      v=c(1);
      for i=2:pp.order           % apply Horner's method
         v=xs.*v+c(i);
      end
   end
   
else              % array input
   
   x=pp.breaks;
   c=pp.coefs.';
   [rx,cx] = size(xx);
	xs=xx(:).';
	tosort=false;
	if any(diff(xs)<0)
      tosort=true;
      [xs,ix]=sort(xs);
	end
	% for each data point, compute its breakpoint interval
	[idx,idx]=histc(xs,x);
	idx(xs<x(1)|~isfinite(xs))=1; % extrapolate using first
	idx(xs>=x(end))=pp.pieces;    % and last polynomial
	
	xs=xs-x(idx);                 % local coordinates
   if pp.order==4                % quick eval for cubic spline
      v=((c(1,idx).*xs + c(2,idx)).*xs + c(3,idx)).*xs +c(4,idx);
   else
		v=c(1,idx);
		for i=2:pp.order           % apply Horner's method
         v=xs.*v+c(i,idx);
		end
   end
	
	if tosort
      v(ix)=v;
	end
	v=reshape(v,rx,cx);
end