How can I define and pass a history prior to t0 to dde23 ?

In the documentation on dde23, it mentions that you can pass a history defined at t ≤ t0 to the solver, but in the examples it seems t ≤ 0 is the default for history. How can I change it from zero to t0?

Here's the example from the documentation:

function ddex1
%DDEX1  Example 1 for DDE23.
%   This is a simple example of Wille' and Baker that illustrates the
%   straightforward formulation, computation, and plotting of the solution 
%   of a system of delay differential equations (DDEs). 
%
%   The differential equations
%
%        y'_1(t) = y_1(t-1)  
%        y'_2(t) = y_1(t-1)+y_2(t-0.2)
%        y'_3(t) = y_2(t)
%
%   are solved on [0, 5] with history y_1(t) = 1, y_2(t) = 1, y_3(t) = 1 for
%   t <= 0. 
%
%   The lags are specified as a vector [1, 0.2], the delay differential
%   equations are coded in the subfunction DDEX1DE, and the history is
%   evaluated by the function DDEX1HIST. Because the history is constant it
%   could be supplied as a vector:
%       sol = dde23(@ddex1de,[1, 0.2],ones(3,1),[0, 5]);
%
%   See also DDE23, FUNCTION_HANDLE.

%   Jacek Kierzenka, Lawrence F. Shampine and Skip Thompson
%   Copyright 1984-2004 The MathWorks, Inc.

sol = dde23(@ddex1de,[1, 0.2],@ddex1hist,[0, 5]);
figure;
plot(sol.x,sol.y)
title('An example of Wille'' and Baker.'); 
xlabel('time t');
ylabel('solution y');

% --------------------------------------------------------------------------

function s = ddex1hist(t)
% Constant history function for DDEX1.
s = ones(3,1);

% --------------------------------------------------------------------------

function dydt = ddex1de(t,y,Z)
% Differential equations function for DDEX1.
ylag1 = Z(:,1);
ylag2 = Z(:,2);
dydt = [ ylag1(1)
         ylag1(1) + ylag2(2)
         y(2)               ];

Here's my own code:

t = [0:3000];
lags = 0.1;
hist = @(t) 0.000000001;
r = 0.1;
rm = 0.015;
Ka = 0.5;
Kb = 7;
K0 = 0.501;
 sol = dde23(@(t,N,Nlag)Bilogistic(t,N,Nlag,Ka,Kb,r,rm,K0),lags,hist,[0,3000]);
 tint = linspace(0,3000);
 yint = deval(sol,tint);
 plot(tint,yint,'r');

I would like to change the history so it reflects the range (-inf,t0).

[Mike AA]

I think I got it I needed to change the integration time span.