Question on condition for AdjustLevelsAndDepthInPlace function

Library Questions
1

Hi,
I am curious why the if-else branch(probably Line645-647) i touched following from src/pke/lib/scheme/ckksrns/ckksrns-leveledshe.cpp still need to add compositeDegree in the condition check after we did the modreduce option?

    if (c1lvl < c2lvl) {
        if (c1depth == 2) {
            if (c2depth == 2) {
                double scf1 = ciphertext1->GetScalingFactor();
                double scf2 = ciphertext2->GetScalingFactor();
                double scf  = cryptoParams->GetScalingFactorReal(c1lvl);
                double q1   = cryptoParams->GetModReduceFactor(sizeQl1 - 1);
                for (uint32_t j = 1; j < compositeDegree; j++) {
                    q1 *= cryptoParams->GetModReduceFactor(sizeQl1 - j - 1);
                }
                EvalMultCoreInPlace(ciphertext1, scf2 / scf1 * q1 / scf);
                ModReduceInternalInPlace(ciphertext1, compositeDegree);
                if (c1lvl + compositeDegree < c2lvl) {
                    LevelReduceInternalInPlace(ciphertext1, c2lvl - c1lvl - compositeDegree);
                }
                ciphertext1->SetScalingFactor(ciphertext2->GetScalingFactor());
}
...
}}

Great thanks for your help.

2

After a more expensive ModReduce was done for ciphertext1, additional RNS limbs in ciphertext1 (as compared to ciphertext2) can be removed by using a cheap LevelReduce method.