From 037cb0951b26442421ed39c193f68eea5fcefcab Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <pavel@cs.unc.edu>
Date: Fri, 21 Mar 2014 01:13:57 -0400
Subject: [PATCH] Built-in rand was causing severe perf issues.

---
 Base/include/MatrixSquare.h | 12 +++++-------
 Base/test/TestMatrix.cpp    |  2 +-
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/Base/include/MatrixSquare.h b/Base/include/MatrixSquare.h
index 99edeca..6e76b40 100644
--- a/Base/include/MatrixSquare.h
+++ b/Base/include/MatrixSquare.h
@@ -50,16 +50,14 @@ namespace FasTC {
     // Returns them in eigVec and eigVal after kMaxNumIterations
     int PowerMethod(VectorBase<T, N> &eigVec,
                     T *eigVal = NULL,
-                    const int kMaxNumIterations = 200,
-                    const unsigned int kSeed = time(NULL)) {
+                    const int kMaxNumIterations = 5) {
 
-      srand(kSeed);
       int numIterations = 0;
 
       VectorBase<T, N> b;
+      T norm = 1.0/sqrt(static_cast<T>(N));
       for(int i = 0; i < N; i++)
-        b[i] = static_cast<T>(rand());
-      b.Normalize();
+        b[i] = norm;
 
       bool badEigenValue = false;
       bool fixed = false;
@@ -82,8 +80,8 @@ namespace FasTC {
           }
 
           VectorBase<T, N> b;
-          for(int i = 0; i < N; i++)
-            b[i] = static_cast<T>(rand());
+          for(int i = 0; i < (N>>1); i++)
+            b[i] = 1;
 
           b.Normalize();
           badEigenValue = true;
diff --git a/Base/test/TestMatrix.cpp b/Base/test/TestMatrix.cpp
index 089c3a0..dbd51c9 100644
--- a/Base/test/TestMatrix.cpp
+++ b/Base/test/TestMatrix.cpp
@@ -252,7 +252,7 @@ TEST(MatrixSquare, PowerMethod) {
 
   double e;
   FasTC::VectorBase<double, 2> x;
-  A.PowerMethod(x, &e, 20, 200);
+  A.PowerMethod(x, &e, 20);
 
   EXPECT_NEAR(x[0], 0.83205f, 0.0002);
   EXPECT_NEAR(x[1], 0.5547f, 0.0002);