I'm having a response like below from FANN
Epochs 1. Current error: 0.2500066161. Bit fail 4.
Epochs 58. Current error: 0.0000930788. Bit fail 0.
what does Bit fail mean here?
The number of fail bits; means the number of output neurons that differ more than the bit fail limit (see fann_get_bit_fail_limit, fann_set_bit_fail_limit).
The bits are counted in all of the training data, so this number can be higher than the number of training data.
This value is now reset by fann_reset_MSE and then updated by all the same functions which also updates the MSE value (e.g. fann_test_data, fann_train_epoch)