SP: use log boosting

does not require parameter

CommonCompilerConfig.cmake

@@ -341,7 +341,7 @@ else()
         set(optimization_flags_cc ${optimization_flags_cc} -pipe -O3)
         set(optimization_flags_lt ${optimization_flags_lt} -O3)
         if(NOT ${CMAKE_SYSTEM_PROCESSOR} STREQUAL "armv7l")
-                set(optimization_flags_cc ${optimization_flags_cc} -mtune=generic)
+                set(optimization_flags_cc ${optimization_flags_cc} -march=native)
         endif()
         if(${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU" AND NOT MINGW)
                 set(optimization_flags_cc ${optimization_flags_cc} -fuse-ld=gold)

src/examples/mnist/MNIST_SP.cpp

@@ -67,7 +67,7 @@ class MNIST {
 
   public:
     UInt verbosity = 1;
-    const UInt train_dataset_iterations = 2u; //epochs somewhat help, at linear time
+    const UInt train_dataset_iterations = 1u; //epochs somewhat help, at linear time
 
 
 void setup() {

src/htm/algorithms/SpatialPooler.cpp

@@ -766,7 +766,8 @@ void applyBoosting_(const UInt i,
 		    const Real boost,
 	            vector<Real>& output) {
   if(boost < htm::Epsilon) return; //skip for disabled boosting
-  output[i] = exp((targetDensity - actualDensity[i]) * boost); //TODO doc this code
+  //output[i] = exp((targetDensity - actualDensity[i]) * boost); //exponential boosting, default for Numenta
+  output[i] = log(actualDensity[i]) / log(targetDensity);
 }
 
 

src/test/unit/algorithms/SpatialPoolerTest.cpp

@@ -980,24 +980,11 @@ TEST(SpatialPoolerTest, testUpdateBoostFactors) {
   sp.getBoostFactors(resultBoostFactors1.data());
   ASSERT_TRUE(check_vector_eq(trueBoostFactors1, resultBoostFactors1));
 
-  Real32 initActiveDutyCycles2[] = {0.1f, 0.3f, 0.02f, 0.04f, 0.7f, 0.12f};
-  Real32 initBoostFactors2[] = {0, 0, 0, 0, 0, 0};
-  vector<Real32> trueBoostFactors2 = {3.10599f, 0.42035f,    6.91251f,
-                                      5.65949f, 0.00769898f, 2.54297f};
-  vector<Real32> resultBoostFactors2(6, 0);
-  sp.setGlobalInhibition(false);
-  sp.setBoostStrength(10);
-  sp.setBoostFactors(initBoostFactors2);
-  sp.setActiveDutyCycles(initActiveDutyCycles2);
-  sp.updateBoostFactors_();
-  sp.getBoostFactors(resultBoostFactors2.data());
-
-  ASSERT_TRUE(check_vector_eq(trueBoostFactors2, resultBoostFactors2));
 
   Real32 initActiveDutyCycles3[] = {0.1f, 0.3f, 0.02f, 0.04f, 0.7f, 0.12f};
   Real initBoostFactors3[] = {0, 0, 0, 0, 0, 0};
-  vector<Real32> trueBoostFactors3 = {1.25441f, 0.840857f, 1.47207f,
-                                      1.41435f, 0.377822f, 1.20523f};
+  vector<Real32> trueBoostFactors3 = {1.49044f, 0.779321f, 2.53222f,
+	                              2.08355f, 0.230873f, 1.37243f};
   vector<Real32> resultBoostFactors3(6, 0);
   sp.setWrapAround(true);
   sp.setGlobalInhibition(false);
@@ -1011,10 +998,11 @@ TEST(SpatialPoolerTest, testUpdateBoostFactors) {
 
   ASSERT_TRUE(check_vector_eq(trueBoostFactors3, resultBoostFactors3));
 
+
   Real32 initActiveDutyCycles4[] = {0.1f, 0.3f, 0.02f, 0.04f, 0.7f, 0.12f};
   Real32 initBoostFactors4[] = {0, 0, 0, 0, 0, 0};
-  vector<Real32> trueBoostFactors4 = {1.94773f, 0.263597f,   4.33476f,
-                                      3.549f,   0.00482795f, 1.59467f};
+  vector<Real32> trueBoostFactors4 = {1.2851f, 0.67195f, 2.18334f,
+	                              1.79649f, 0.199064f, 1.18334f};
   vector<Real32> resultBoostFactors4(6, 0);
   sp.setGlobalInhibition(true);
   sp.setBoostStrength(10);
@@ -2103,14 +2091,16 @@ TEST(SpatialPoolerTest, testConstructorVsInitialize) {
 TEST(SpatialPoolerTest, ExactOutput) { 
   // Silver is an SDR that is loaded by direct initalization from a vector.
   SDR silver_sdr({ 200 });
-  SDR_sparse_t data = {23, 71, 113, 118, 129, 172, 178, 182, 185, 190};
+  SDR_sparse_t data = {
+    12, 51, 81, 113, 129, 133, 172, 175, 178, 190
+  };
   silver_sdr.setSparse(data);
 
 
   // Gold tests initalizing an SDR from a manually created string in JSON format.
 	// hint: you can generate this string using
 	//       silver_sdr.save(std::cout, JSON);
-  string gold = "{\"dimensions\": [200],\"sparse\": [23,71,113,118,129,172,178,182,185,190]}";
+  string gold = "{\"dimensions\": [200],\"sparse\": [12, 51, 81, 113, 129, 133, 172, 175, 178, 190]}";
   std::stringstream gold_stream( gold );
   SDR gold_sdr;
   gold_sdr.load( gold_stream, JSON );