function d1 = bksupk(ny,fid,jcf,icc1)

% function d1 = bksupk(ny,fid,jcf,icc1)
% Solves deterministic models recursively by backsubstitution for k leads/lags
%
% INPUTS
%    ny:             number of endogenous variables
%    fid:            saves the elements above the diagonal
%    jcf:            variables index forward
%    icc1:           jacobian column forward
%
% OUTPUTS
%    d1:             vector of backsubstitution results
%
% SPECIAL REQUIREMENTS
%    none
%  
% part of DYNARE, copyright Dynare Team (2003-2007)
% Gnu Public License.

global M_ options_

icf = [1:jcf-1] ;
ir = [(options_.periods-1)*ny+1:ny*options_.periods] ;
irf = icc1+(options_.periods-1)*ny ;
d1 = zeros(options_.periods*ny,1) ;

ofs = (((options_.periods-1)*ny+1)-1)*jcf*8 ;
junk = fseek(fid,ofs,-1) ;
c = fread(fid,[jcf,ny],'float64')';

d1(ir) = c(:,jcf) ;
ir = ir-ny ;

i = 2 ;

while i <= M_.maximum_lead | i <= options_.periods
	irf1 = selif(irf,irf<=options_.periods*ny) ;

	ofs = (((options_.periods-i)*ny+1)-1)*jcf*8 ;
	junk = fseek(fid,ofs,-1) ;
	c = fread(fid,[jcf,ny],'float64')' ;

	d1(ir) = c(:,jcf) - c(:,1:size(irf1,1))*d1(irf1) ;
	ir = ir - ny ;
	irf = irf - ny ;
	i = i + 1 ;
end

while i <= options_.periods

	ofs = (((options_.periods-i)*ny+1)-1)*jcf*8 ;
	junk = fseek(fid,ofs,-1) ;
	c = fread(fid,[jcf,ny],'float64')' ;

	d1(ir) = c(:,jcf)-c(:,icf)*d1(irf) ;
	ir = ir-ny ;			
	irf = irf-ny ;
	i = i+1;
end

return ;