From 74eb2bfbef5d736e8c024d735562ea6c536d78f1 Mon Sep 17 00:00:00 2001
From: Connor Olding <cloningdonor@gmail.com>
Date: Tue, 12 Jun 2018 20:51:08 +0200
Subject: [PATCH] fix antithetic ARS

---
 ars.lua | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/ars.lua b/ars.lua
index 99e3c46..2e2eddd 100644
--- a/ars.lua
+++ b/ars.lua
@@ -105,12 +105,13 @@ function Ars:ask(graycode)
         local asking = zeros(self.dims)
         local noisy = zeros(self.dims)
         asked[i] = asking
+        noise[i] = noisy
 
         if self.antithetic and i % 2 == 0 then
-            for j, v in ipairs(self._params) do
-                asking[i] = v - noisy[j]
+            local old_noisy = noise[i - 1]
+            for j, v in ipairs(old_noisy) do
+                noisy[j] = -v
             end
-
         else
             if graycode ~= nil then
                 for j = 1, self.dims do
@@ -124,13 +125,11 @@ function Ars:ask(graycode)
                     noisy[j] = self.sigma * nn.normal()
                 end
             end
-
-            for j, v in ipairs(self._params) do
-                asking[j] = v + noisy[j]
-            end
         end
 
-        noise[i] = noisy
+        for j, v in ipairs(self._params) do
+            asking[j] = v + noisy[j]
+        end
     end
 
     self.noise = noise