function [tout,yout]=eultest(x0,xf,y0,deltax)

% [tout,yout]=eulertest(x0,xf,y0,deltax)
%
% Input
%
% scalar x0 is initial value
% scalar final xf>x0
% scalar initial value y0<xf
% scalar stepsize deltax
%
% Output 
%
% vector xout of x values
% vector of yout approximate values for those x's
% exact values solve y'=-x/y and lie on a circle

h=deltax;
x=x0;
y=y0;
xout=x0;  % first element of outputs
yout=y0;

while (x< xf-h)
    slope = -x/y;
    x=x+h;         %  new x coord 
    y=y+h*slope;   %  new y 
    xout=[xout  x]; % adjoin one element to the row of x's
    yout=[yout y]; % adjoing an element to the row of y's
end;    % end the while loop

% compute value at xf

slope = -x/y;
k=xf-x;
x=xf;
y=y+k*slope; 
xout=[xout  x]; % adjoin last element to the row of x's
yout=[yout y]; % adjoing last element to the row of y's

plot(xout,yout,xout,yout,'*')

