iguess0.m

function [IG, k] = iguess0(Q, n, k)

% function [IG,k]=iguess(Q). This routine takes a set of data points, Q;
% picks out subset of the data point for knot points, P; computes the
% position of the knot points,k; computes the initial distances, dt, to
% place the interior control points, C, which are also computed; compute
% the angles, ang, of the unit tangent vectors at each knot point; and
% assembles the vector IG of paramaters P, ang, and dt, for the curve.
% The routine returns the "vector" of parmeters and plots the curve,
% its polygon, and the data points in Q. It was written by M. R. Holmes
% and revised by E. J. Lane.

global dpkpc;
[r ,m] = size(Q);

% Q  = datapoints (2xm)
% n  = The number of knotpoints
% k  = default know positions (indices 1...m)
if nargin < 3
    k = defk(m,n); % Calls for default knot position.
end

dpkpc = k; 		    % Position of knot points passed globally.
P   = knots(Q,k); 	% call to compute the knotpoints.
dt  = distEJL(P); 	% Call to compute the distance between
                    % successive knot points.

ang = tang(Q,k); 	% Call to compute the angles for
% the unit tangent vectors.

C   = ctpts(P,ang,dt);	% Call to compute the control points;
% for the curve.

figure;
pltC(C,Q,P); 		% Call to plot the initial guess curve,
% its control polygon, and points in Q.
title('Plot of Initial Guess curve');

% Assemble the composite vector of the initial guess curve parameters
IG = [P(1,:) P(2,:) ang dt(1,:) dt(2,:)];