Add quadratic interterpolation

Not usable at all, worse than mean value.

1 files changed, 23 insertions, 0 deletions

diff --git a/quad_regress_pred.m b/quad_regress_pred.m
new file mode 100644
index 0000000..aef8822
--- /dev/null
+++ b/quad_regress_pred.m
@@ -0,0 +1,23 @@
+function pred = quad_regress_pred(price, quantity)
+
+	days = size(price, 1) - size(quantity, 1);
+	product_count = size(price, 2);
+	test_count = size(quantity, 1);
+	test_set = 1:test_count;
+	pred_set = test_count+1:size(price, 1);
+
+	pred = zeros(days, product_count);
+	for i = 1:product_count
+		[a,b,c] = regress2(price(test_set, i), quantity(test_set, i));
+		pred(:, i) = a .* price(pred_set, i).^2 + b * price(pred_set, i) + c;
+	end
+
+endfunction
+
+
+function [a,b,c] = regress2(x, y)
+	abc = [ x.^2 x ones(length(x), 1) ] \ y;
+	a = abc(1);
+	b = abc(2);
+	c = abc(3);
+endfunction