diff --git a/src/main/java/org/apache/sysds/hops/codegen/SpoofCompiler.java b/src/main/java/org/apache/sysds/hops/codegen/SpoofCompiler.java
index 6f107d7..2d50056 100644
--- a/src/main/java/org/apache/sysds/hops/codegen/SpoofCompiler.java
+++ b/src/main/java/org/apache/sysds/hops/codegen/SpoofCompiler.java
@@ -30,8 +30,6 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.api.DMLScript;
 import org.apache.sysds.common.Types.ExecMode;
 import org.apache.sysds.common.Types.OpOp1;
diff --git a/src/main/java/org/apache/sysds/hops/cost/CostEstimationWrapper.java b/src/main/java/org/apache/sysds/hops/cost/CostEstimationWrapper.java
index 8aee81a..f8d6a2d 100644
--- a/src/main/java/org/apache/sysds/hops/cost/CostEstimationWrapper.java
+++ b/src/main/java/org/apache/sysds/hops/cost/CostEstimationWrapper.java
@@ -23,8 +23,6 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.runtime.DMLRuntimeException;
 import org.apache.sysds.runtime.controlprogram.LocalVariableMap;
 import org.apache.sysds.runtime.controlprogram.Program;
diff --git a/src/main/java/org/apache/sysds/hops/rewrite/ProgramRewriter.java b/src/main/java/org/apache/sysds/hops/rewrite/ProgramRewriter.java
index f568c9d..87df183 100644
--- a/src/main/java/org/apache/sysds/hops/rewrite/ProgramRewriter.java
+++ b/src/main/java/org/apache/sysds/hops/rewrite/ProgramRewriter.java
@@ -22,8 +22,6 @@
 import java.util.ArrayList;
 import java.util.List;
 
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.api.DMLScript;
 import org.apache.sysds.conf.ConfigurationManager;
 import org.apache.sysds.conf.CompilerConfig.ConfigType;
diff --git a/src/main/java/org/apache/sysds/runtime/controlprogram/federated/FederatedData.java b/src/main/java/org/apache/sysds/runtime/controlprogram/federated/FederatedData.java
index 5e83dc2..2c5f902 100644
--- a/src/main/java/org/apache/sysds/runtime/controlprogram/federated/FederatedData.java
+++ b/src/main/java/org/apache/sysds/runtime/controlprogram/federated/FederatedData.java
@@ -36,7 +36,6 @@
 import org.apache.sysds.conf.DMLConfig;
 import org.apache.sysds.runtime.DMLRuntimeException;
 import org.apache.sysds.runtime.controlprogram.federated.FederatedRequest.RequestType;
-import org.apache.sysds.utils.Statistics;
 
 import java.net.InetSocketAddress;
 import java.util.concurrent.Future;
diff --git a/src/main/java/org/apache/sysds/runtime/lineage/LineageRewriteReuse.java b/src/main/java/org/apache/sysds/runtime/lineage/LineageRewriteReuse.java
index ddd8abe..60b2eea 100644
--- a/src/main/java/org/apache/sysds/runtime/lineage/LineageRewriteReuse.java
+++ b/src/main/java/org/apache/sysds/runtime/lineage/LineageRewriteReuse.java
@@ -26,8 +26,6 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.api.DMLScript;
 import org.apache.sysds.common.Types.AggOp;
 import org.apache.sysds.common.Types.Direction;
diff --git a/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCUDA.java b/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCUDA.java
index 95af608..dc5a1f0 100644
--- a/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCUDA.java
+++ b/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCUDA.java
@@ -21,8 +21,6 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.api.DMLScript;
 import org.apache.sysds.runtime.DMLRuntimeException;
 import org.apache.sysds.runtime.controlprogram.caching.MatrixObject;
diff --git a/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCountDistinct.java b/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCountDistinct.java
index 474c323..0ae1b92 100644
--- a/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCountDistinct.java
+++ b/src/main/java/org/apache/sysds/runtime/matrix/data/LibMatrixCountDistinct.java
@@ -28,8 +28,6 @@
 import org.apache.commons.lang.NotImplementedException;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.api.DMLException;
 import org.apache.sysds.runtime.DMLRuntimeException;
 import org.apache.sysds.runtime.matrix.operators.CountDistinctOperator;
diff --git a/src/main/java/org/apache/sysds/runtime/matrix/data/MatrixBlock.java b/src/main/java/org/apache/sysds/runtime/matrix/data/MatrixBlock.java
index a879de3..45a0965 100644
--- a/src/main/java/org/apache/sysds/runtime/matrix/data/MatrixBlock.java
+++ b/src/main/java/org/apache/sysds/runtime/matrix/data/MatrixBlock.java
@@ -637,15 +637,16 @@
 	}
 	
 	public boolean containsValue(double pattern) {
+		//fast paths: infer from meta data only
 		if(isEmptyBlock(true))
 			return pattern==0;
+		if( nonZeros < getLength() && pattern == 0 )
+			return true;
 		
 		//make a pass over the data to determine if it includes the
 		//pattern, with early abort as soon as the pattern is found
 		boolean NaNpattern = Double.isNaN(pattern);
 		if( isInSparseFormat() ) {
-			if( nonZeros < getLength() && pattern == 0 )
-				return true;
 			SparseBlock sb = getSparseBlock();
 			for(int i=0; i<rlen; i++) {
 				if( sb.isEmpty(i) ) continue;
@@ -661,7 +662,8 @@
 			DenseBlock db = getDenseBlock();
 			for(int i=0; i<rlen; i++) {
 				double[] vals = db.values(i);
-				for(int j=0; j<clen; j++)
+				int pos = db.pos(i);
+				for(int j=pos; j<pos+clen; j++)
 					if(vals[j]==pattern || (NaNpattern && Double.isNaN(vals[j])))
 						return true;
 			}
diff --git a/src/main/java/org/apache/sysds/utils/NativeHelper.java b/src/main/java/org/apache/sysds/utils/NativeHelper.java
index 25510c7..59fd243 100644
--- a/src/main/java/org/apache/sysds/utils/NativeHelper.java
+++ b/src/main/java/org/apache/sysds/utils/NativeHelper.java
@@ -23,8 +23,6 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.apache.log4j.Level;
-import org.apache.log4j.Logger;
 import org.apache.sysds.conf.ConfigurationManager;
 import org.apache.sysds.conf.DMLConfig;
 import org.apache.sysds.hops.OptimizerUtils;
diff --git a/src/test/java/org/apache/sysds/test/functions/builtin/BuiltinDBSCANTest.java b/src/test/java/org/apache/sysds/test/functions/builtin/BuiltinDBSCANTest.java
index 401229a..980f644 100644
--- a/src/test/java/org/apache/sysds/test/functions/builtin/BuiltinDBSCANTest.java
+++ b/src/test/java/org/apache/sysds/test/functions/builtin/BuiltinDBSCANTest.java
@@ -38,7 +38,7 @@
 
 	private final static double eps = 1e-3;
 	private final static int rows = 1700;
-	private final static double spDense = 0.99;
+	//private final static double spDense = 0.99;
 
 	private final static double epsDBSCAN = 1;
 	private final static int minPts = 5;
@@ -90,4 +90,4 @@
 			rtplatform = platformOld;
 		}
 	}
-}
\ No newline at end of file
+}