void gradient(INT e1_a, INT e2_a, INT rel_a, INT e1_b, INT e2_b, INT rel_b) {
    INT lasta1 = e1_a * dimension;
    INT lasta2 = e2_a * dimension;
    INT lastar = rel_a * dimension;
    INT lastb1 = e1_b * dimension;
    INT lastb2 = e2_b * dimension;
    INT lastbr = rel_b * dimension;
    for (INT ii=0; ii  < dimension; ii++) {
        REAL x;
        x = (entityVec[lasta2 + ii] - entityVec[lasta1 + ii] - relationVec[lastar + ii]);
        if (x > 0)
            x = -alpha;
        else
            x = alpha;
        relationVec[lastar + ii] -= x;
        entityVec[lasta1 + ii] -= x;
        entityVec[lasta2 + ii] += x;
        x = (entityVec[lastb2 + ii] - entityVec[lastb1 + ii] - relationVec[lastbr + ii]);
        if (x > 0)
            x = alpha;
        else
            x = -alpha;
        relationVec[lastbr + ii] -=  x;
        entityVec[lastb1 + ii] -= x;
        entityVec[lastb2 + ii] += x;
    }
}

void train_kb(INT e1_a, INT e2_a, INT rel_a, INT e1_b, INT e2_b, INT rel_b) {
    REAL sum1 = calc_sum(e1_a, e2_a, rel_a);
    REAL sum2 = calc_sum(e1_b, e2_b, rel_b);
        //printf("                              %f %f\r", sum1, sum2);
    if (sum1 + margin > sum2) {
        //res += margin + sum1 - sum2;
        //gradient(e1_a, e2_a, rel_a, e1_b, e2_b, rel_b);
        res += (margin+sum1-sum2) * (margin+sum1-sum2) * 0.5;
        gradient_l2(e1_a, e2_a, rel_a, e1_b, e2_b, rel_b);
    }
}