delta_b = delta_b.columnSums().divi(nbr_samples);
delta_w.divi(nbr_samples);
if (my_config.isUseRegularization()) {
if (0 != my_config.getLamada1()) {
delta_w.addi(MatrixFunctions.signum(my_w).mmuli(my_config.getLamada1()));
delta_b.addi(MatrixFunctions.signum(my_b).transpose().mmuli(my_config.getLamada1()));
}
if (0 != my_config.getLamada2()) {
delta_w.addi(my_w.mmul(my_config.getLamada2()));
delta_b.addi(my_b.transpose().mmul(my_config.getLamada2()));