<input type="button" value="Y (0,4)" onclick="zoomGraphY(0,4)">
<input type="button" value="Y (2,4)" onclick="zoomGraphY(2,4)">
<input type="button" value="Y (0,2)" onclick="zoomGraphY(0,2)">
<input type="button" value="Y (0,4)" onclick="zoomGraphY(0,4)">
<input type="button" value="Y (2,4)" onclick="zoomGraphY(2,4)">
<input type="button" value="Y (0,2)" onclick="zoomGraphY(0,2)">