error Descriptor SURF c++ OpenCV on Android

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HI when I try to call a native method Features2D + Homography to find a known object I had errors telque

double dist = matches[i].distance;
matches[i].distance < 3*min_dist
good_matches.push_back( matches[i]);

line

console :

Compile++ thumb : native_sample <= jni_part.cpp Prebuilt : libgnustl_static.a <= <ndk>/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi-v7a/ SharedLibrary : libnative_sample.so Install : libnative_sample.so => libs/armeabi-v7a/libnative_sample.so mirlo06@mirlo06-Satellite-L500:~/OpenCV4android/samples/tutorial-3-native$ /opt/android-ndk/ndk-build Compile++ thumb : native_sample <= jni_part.cpp Prebuilt : libgnustl_static.a <= <ndk>/sources/cxx-stl/gnu-libstdc++/4.6/libs/armeabi-v7a/ SharedLibrary : libnative_sample.so /opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: warning: hidden symbol '__aeabi_atexit' in ./obj/local/armeabi-v7a/libgnustl_static.a(atexit_arm.o) is referenced by DSO ../../sdk/native/jni/../libs/armeabi-v7a/libopencv_java.so /opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi-v7a/objs/native_sample/jni_part.o: in function cv::SURF::~SURF():../../sdk/native/jni/include/opencv2/nonfree/features2d.hpp:107: error: undefined reference to 'vtable for cv::SURF' /opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi-v7a/objs/native_sample/jni_part.o: in function cv::SURF::~SURF():../../sdk/native/jni/include/opencv2/nonfree/features2d.hpp:107: error: undefined reference to 'VTT for cv::SURF' /opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi-v7a/objs/native_sample/jni_part.o: in function Java_org_opencv_samples_tutorial3_Sample3Native_FindFeatures:jni/jni_part.cpp:26: error: undefined reference to 'cv::SURF::SURF(double, int, int, bool, bool)' /opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld: ./obj/local/armeabi-v7a/objs/native_sample/jni_part.o: in function Java_org_opencv_samples_tutorial3_Sample3Native_FindFeatures:jni/jni_part.cpp:34: error: undefined reference to 'cv::SURF::SURF()' collect2: ld returned 1 exit status make: * [obj/local/armeabi-v7a/libnative_sample.so] Error 1

here is the code

#include <jni.h>
#include <opencv2/core/core.hpp>
#include <opencv2/nonfree/features2d.hpp>
#include <opencv2/imgproc/imgproc.hpp>

#include <opencv2/highgui/highgui.hpp>
#include <opencv2/calib3d/calib3d.hpp>
#include <vector>


using namespace cv;
using namespace std;

extern "C" {
JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial3_Sample3Native_FindFeatures(JNIEnv*, jobject, jlong addrGray, jlong addrRgba);

JNIEXPORT void JNICALL Java_org_opencv_samples_tutorial3_Sample3Native_FindFeatures(JNIEnv*, jobject, jlong addrGray, jlong addrRgba)
{

    Mat& img_object  = *(Mat*)addrGray;
    Mat& img_scene = *(Mat*)addrRgba;
    int minHessian = 400;

      SurfFeatureDetector detector( minHessian );

      vector<KeyPoint> keypoints_object, keypoints_scene;

      detector.detect( img_object, keypoints_object );
      detector.detect( img_scene, keypoints_scene );

      //-- Step 2: Calculate descriptors (feature vectors)
      SurfDescriptorExtractor extractor;

      Mat descriptors_object, descriptors_scene;

      extractor.compute( img_object, keypoints_object, descriptors_object );
      extractor.compute( img_scene, keypoints_scene, descriptors_scene );

      //-- Step 3: Matching descriptor vectors using FLANN matcher
      FlannBasedMatcher matcher;
      vector< DMatch > matches;
      matcher.match( descriptors_object, descriptors_scene, matches );

      double max_dist = 0; double min_dist = 100;

      //-- Quick calculation of max and min distances between keypoints
      for( int i = 0; i < descriptors_object.rows; i++ )
      { double dist = matches[i].distance;
        if( dist < min_dist ) min_dist = dist;
        if( dist > max_dist ) max_dist = dist;
      }



      //-- Draw only "good" matches (i.e. whose distance is less than 3*min_dist )
      vector< DMatch > good_matches;

      for( int i = 0; i < descriptors_object.rows; i ...