2016-12-12 06:02:37 -0500 received badge ● Editor (source) 2016-12-09 05:11:08 -0500 asked a question ANN_MLP segmentation fault on predict() if not directly preceeded by train() Hey, i am using c++ OpenCV 3.1 on Ubuntu Xenial. I think i found a bug in OpenCV but want to reassure that I am not missing something. I have code that first trains my ANN_MLP with training data in one method. Then, on user input a new sample is generated and forwarded to my predict() wrapping method. This is how a snippet looks Mat_ responses = Mat::zeros(data.rows, categories.size(), data.type()); (...) //fillup responses Mat_ layer_sizes(1, 3); //gets filled up (...) //fillup layer_sizes mlp = ml::ANN_MLP::create(); // mlp is a class variable mlp->setActivationFunction(ml::ANN_MLP::SIGMOID_SYM, 0.1, 0.1); mlp->setTrainMethod(ml::ANN_MLP::BACKPROP, 0.1, 0.1); mlp->setLayerSizes(layer_sizes); traindata = ml::TrainData::create(data, ml::ROW_SAMPLE, responses); //traindata is a class variable mlp->train(traindata);  training works well here! Now when I go to predict within another method of the same class and I take a row from the trained set I get a segmentation fault except I do it this way mlp->setActivationFunction(ml::ANN_MLP::SIGMOID_SYM, 0.1, 0.1); mlp->train(traindata); mlp->predict(feature, results);  As you see I have to set the activation function again and train again. This is really annoying. It may be somewhat related to the following bug: http://code.opencv.org/issues/4251 Because when I run the program with gdb I get a message containing icv_y8_ownMinMaxIndx_32f_C1R_U8_2  related to an error. Now I think that ANN_MLP internally misses to internally store the activation function as well as the trained data (or parts of this). What do you think? Here is the gdb bt output. Sadly, i cannot compile OpenCV in debug mode.  Thread 1 "xxx" received signal SIGSEGV, Segmentation fault. 0x00007ffff5a59e9a in icv_y8_ownMinMaxIndx_32f_C1R_U8_2 () from /xxx/ros/kinetic/lib/libopencv_core3.so.3.1 (gdb) bt #0 0x00007ffff5a59e9a in icv_y8_ownMinMaxIndx_32f_C1R_U8_2 () from /xxx/ros/kinetic/lib/libopencv_core3.so.3.1 (...) #10 0x00000000011dc380 in ?? () #11 0x00007fffffff9cb8 in ?? () #12 0x0000000000000008 in ?? () #13 0x00007ffff57ce5d7 in icv_y8_ippiMinMaxIndx_32f_C1R () from /xxx/ros/kinetic/lib/libopencv_core3.so.3.1 #14 0x00007ffff5490f97 in cv::minMaxIdx(cv::_InputArray const&, double*, double*, int*, int*, cv::_InputArray const&) () from /xxx/ros/kinetic/lib/libopencv_core3.so.3.1