Why does the "ffm_predict" function return "1/(1+exp(-t))"?

[Zhen Zeng]

I'm confused about the "ffm_predict" function in the ffm.cpp :

ffm_float ffm_predict(ffm_node *begin, ffm_node *end, ffm_model &model) {
    ffm_float r = 1;
    if(model.normalization) {
        r = 0;
        for(ffm_node *N = begin; N != end; N++)
            r += N->v*N->v; 
        r = 1/r;
    }

    ffm_float t = wTx(begin, end, r, model);

    return 1/(1+exp(-t));
}

After reading the paper, "Field-aware Factorization Machines for CTR Prediction", I think the return value should be the variable t, not be the value of 1/(1+exp(-t)). Could you answer my doubt ?