From a6b42aad6a2eab50d2f1fac4bfea895fdf9891d0 Mon Sep 17 00:00:00 2001
From: conrad <conrad@localhost.localdomain>
Date: Mon, 12 Apr 2021 12:45:08 +1000
Subject: [PATCH] use old method to ensure same sequence for ARMA_RNG_ALT randn

---
 include/armadillo_bits/arma_rng.hpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/armadillo_bits/arma_rng.hpp b/include/armadillo_bits/arma_rng.hpp
index e7c92f37..3846cfb8 100644
--- a/include/armadillo_bits/arma_rng.hpp
+++ b/include/armadillo_bits/arma_rng.hpp
@@ -489,7 +489,13 @@ struct arma_rng::randn
     {
     #if defined(ARMA_RNG_ALT)
       {
-      for(uword i=0; i < N; ++i)  { mem[i] = eT( arma_rng_alt::randn_val() ); }
+      // NOTE: old method to avoid regressions in user code that assumes specific sequence
+      
+      uword i, j;
+      
+      for(i=0, j=1; j < N; i+=2, j+=2)  { arma_rng_alt::randn_dual_val( mem[i], mem[j] ); }
+      
+      if(i < N)  { mem[i] = eT( arma_rng_alt::randn_val() ); }
       }
     #elif defined(ARMA_USE_EXTERN_RNG)
       {