FastText

fasttext.cc

void Model::computeOutputSoftmax(Vector& hidden, Vector& output) const {
  if (quant_ && args_->qout) {
    output.mul(*qwo_, hidden);
  } else {
    output.mul(*wo_, hidden);
  }
  real max = output[0], z = 0.0;
  for (int32_t i = 0; i < osz_; i++) {
    max = std::max(output[i], max);
  }
  for (int32_t i = 0; i < osz_; i++) {
    output[i] = exp(output[i] - max);
    z += output[i];
  }
  for (int32_t i = 0; i < osz_; i++) {
    output[i] /= z;
  }
}

void Model::computeOutputSoftmax() {
  computeOutputSoftmax(hidden_, output_);
}

real Model::softmax(int32_t target, real lr) {
  grad_.zero();
  computeOutputSoftmax();
  for (int32_t i = 0; i < osz_; i++) {
    real label = (i == target) ? 1.0 : 0.0;
    real alpha = lr * (label - output_[i]);
    grad_.addRow(*wo_, i, alpha);
    wo_->addRow(hidden_, i, alpha);
  }
  return -log(output_[target]);
}