# Number of tower in CKKS FIXEDMANUAL

**URL:** <https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851>\
**Category:** Library Questions\
**Created:** [January 30, 2025, 9:51pm UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851 "2025-01-30T21:51:52Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![malioboro](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@malioboro](https://openfhe.discourse.group/u/malioboro)\
**Post date:** [January 30, 2025, 9:51pm UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/1 "2025-01-30T21:51:52Z")

</div>

I tried to print the number of towers of c (fresh ciphertext) in the example code advanced-real-numbers.cpp. The code set the multiplicative depth = 5, so I expected I would get the number of towers = 6, but it turns out I got 7. So does it mean that in FIXEDMANUAL OpenFHE, an auxiliary tower is also implemented? Is there a way to use FIXEDMANUAL without an auxiliary tower?

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<div class="post-metadata">

**Author:** ![Caesar](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/caesar/32/63_2.png) [@Caesar](https://openfhe.discourse.group/u/Caesar)\
**Post date:** [January 31, 2025, 1:56am UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/2 "2025-01-31T01:56:48Z")

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Please share a minimum working example so we can help you better. Also, share the logic you use to count the number of towers.

In `FIXEDMANUAL`, `FIXEDAUTO`, or `FLEXIBLEAUTO` modes, the number of the primary towers in the ciphertext modulus equals `multiplicative_depth + 1`. Only in the `FLEXIBLEAUTOEXT` mode (the default scaling mode in the OpenFHE implementation of CKKS), the number of towers will be `multiplicative_depth + 2`.

I think you are using the default scaling technique or not counting the towers correctly.

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<div class="post-metadata">

**Author:** ![malioboro](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@malioboro](https://openfhe.discourse.group/u/malioboro)\
**Post date:** [January 31, 2025, 5:25am UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/3 "2025-01-31T05:25:35Z")

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I use the original `advanced-real-numbers.cpp` in `/src/pke/examples`. Then add this function:

```auto
void printCPinfo(Ciphertext<DCRTPoly>& c1){
    std::cout << "CIPHERTEXT size: " << c1->GetElements().size() << " x " << c1->GetElements()[0].GetAllElements().size() << " x " << c1->GetElements()[0].GetAllElements()[0].GetValues().GetLength() << std::endl;
}

```

I called it inside `ManualRescaleDemo`:

```auto
void ManualRescaleDemo(ScalingTechnique scalTech) {
...
    printCPinfo(c);
    auto c2_depth2 = cc->EvalMult(c, c);
    auto c2_depth1 = cc->Rescale(c2_depth2);

```

it prints:

```auto
...
CIPHERTEXT size: 2 x 7 x 32768
...

```

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<div class="post-metadata">

**Author:** ![Caesar](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/caesar/32/63_2.png) [@Caesar](https://openfhe.discourse.group/u/Caesar)\
**Post date:** [January 31, 2025, 3:25pm UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/4 "2025-01-31T15:25:12Z")

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That example uses multiple scaling techniques, see below. You may be confusing them.

```auto
 AutomaticRescaleDemo(FLEXIBLEAUTO);
 // default
 AutomaticRescaleDemo(FLEXIBLEAUTOEXT);
 AutomaticRescaleDemo(FIXEDAUTO);
 ManualRescaleDemo(FIXEDMANUAL);

```

Can you use a simpler example like “simple-real-numbers.cpp” and specify the scaling technique explicitly via:  
`parameters.SetScalingTechnique(ScalingTechnique::FIXEDMANUAL);`

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<div class="post-metadata">

**Author:** ![malioboro](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@malioboro](https://openfhe.discourse.group/u/malioboro)\
**Post date:** [January 31, 2025, 3:53pm UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/5 "2025-01-31T15:53:11Z")

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Hmm… I tried to remove everything from the codes. Here is my full code (~45 lines) by deleting some unnecessary parts from advanced-real-numbers.cpp:

```auto

#define PROFILE
#include "openfhe.h"
using namespace lbcrypto;

void ManualRescaleDemo(ScalingTechnique scalTech);

void printCPinfo(Ciphertext<DCRTPoly>& c1){
    std::cout << "CIPHERTEXT size: " << c1->GetElements().size() << " x " << c1->GetElements()[0].GetAllElements().size() << " x " << c1->GetElements()[0].GetAllElements()[0].GetValues().GetLength() << std::endl;
}

int main(int argc, char* argv[]) {
    ManualRescaleDemo(FIXEDMANUAL);
    return 0;
}

void ManualRescaleDemo(ScalingTechnique scalTech) {
    std::cout << "\n\n\n ===== FixedManualDemo ============= " << std::endl;

    uint32_t batchSize = 8;
    CCParams<CryptoContextCKKSRNS> parameters;
    parameters.SetMultiplicativeDepth(5);
    parameters.SetScalingModSize(50);
    parameters.SetBatchSize(batchSize);

    CryptoContext<DCRTPoly> cc = GenCryptoContext(parameters);

    std::cout << "CKKS scheme is using ring dimension " << cc->GetRingDimension() << std::endl << std::endl;

    cc->Enable(PKE);
    cc->Enable(KEYSWITCH);
    cc->Enable(LEVELEDSHE);

    auto keys = cc->KeyGen();
    cc->EvalMultKeyGen(keys.secretKey);

    // Input
    std::vector<double> x = {1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07};
    Plaintext ptxt = cc->MakeCKKSPackedPlaintext(x);

    std::cout << "Input x: " << ptxt << std::endl;

    auto c = cc->Encrypt(keys.publicKey, ptxt);

    printCPinfo(c);
}

```

Output:

```auto
 ===== FixedManualDemo ============= 
CKKS scheme is using ring dimension 32768

Input x: (1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, ... ); Estimated precision: 50 bits

CIPHERTEXT size: 2 x 7 x 32768

```

I save it as a different file, and call it in CMakeList:

```auto
add_executable( adv-debug adv-debug.cpp )

```

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<div class="post-metadata">

**Author:** ![malioboro](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@malioboro](https://openfhe.discourse.group/u/malioboro)\
**Post date:** [January 31, 2025, 4:14pm UTC](https://openfhe.discourse.group/t/number-of-tower-in-ckks-fixedmanual/1851/6 "2025-01-31T16:14:12Z")

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Oh, I found it! There is no `parameters.SetScalingTechnique(scalTech);` in `ManualRescaleDemo()` in the example code. So it runs with the default scaling technique, FLEXIBLEAUTOEXT

I think I will make an issue/pull request for this! Thank you!