="radio" name="approx" id="a_2" checked value="Move"><label for="a_2">move a point.</label> &nbsp;
		<button type="button" style="width: 120pt;" onclick="undo_last_for_approximation()"><nobr>Remove last</nobr></button>
		<button type="button" style="width: 120pt;" onclick="reset_all_for_approximation()"><nobr>Reset all</nobr></button>
	</div>
	<div id="approximation_formula" class="formula">
	</div>
	<p>
The matrix comes from the <a href="https://en.wikipedia.org/wiki/Polynomial_least_squares#Polynomial_lea