function [begin,endd,gravity,maxim,intf,compac,target]=dt_phi(fil,P)
% Syntax: [begin,endd,gravity,maxim,intf,compac,target]=dt_phi(fil,P);
%     or: [begin,endd,gravity,maxim,intf,compac,target]=dt_phi(fil);
%
% Reading one target and interpolation function in Frederic Bimbot's temporal
% decomposition xxx.ph? files.
% fil - file descriptor (file must be opened in read mode)
% P   - number of coefficients in vector (optional). Default 10.
%
% begin   - first frame of interpolation function (in Matlab indexing)
% endd    - last frame of interpolation function (in Matlab indexing)
% gravity - center of gravity of interpolation function (in Matlab indexing)
% maxim   - index of maximum of interpolation function (in Matlab indexing)
% intf    - interpolation function. Line vector of length end-begin+1.
% compac  - compacity of interpol function.
% target  - target. Column vector of length P.

if nargin==1
  P=10;
end

%%% reading and checking the end of file

[begin, ok]=fread(fil, 1, 'short');
if ok ~= 1,
  begin=-1; endd=0; gravity=0; maxim=0; intf=[]; compac=0; target=[];
  return;
end

%%%  well, can read the rest:

endd=fread(fil, 1, 'short');
gravity=fread(fil, 1, 'short');
maxim=fread(fil, 1, 'short');

%%% everything is already "matlab-indexed" !!!
len=endd-begin+1;

intf=fread(fil, [1,len], 'double');
compac=fread(fil, 1, 'double');
target=fread(fil, [P, 1], 'double');

%%% that should be all...