function [x0,x1,y0,y1] = pickaxes(xvalues,yvalues)
x0=xvalues(1);
nobs = length(xvalues);
x1=xvalues(nobs);
maxy = max(yvalues);
miny = min(yvalues);
y0 = miny - .05*abs(miny);
if (miny>0 & y0<0)
y0 = 0;
end
y1 = maxy + .05*abs(maxy);