# Complex Number Multiplication

**URL:** <https://openfhe.discourse.group/t/complex-number-multiplication/2173>\
**Category:** Library Questions\
**Created:** [September 15, 2025, 6:26pm UTC](https://openfhe.discourse.group/t/complex-number-multiplication/2173 "2025-09-15T18:26:41Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![div](https://avatars.discourse-cdn.com/v4/letter/d/838e76/32.png) [@div](https://openfhe.discourse.group/u/div)\
**Post date:** [September 15, 2025, 6:26pm UTC](https://openfhe.discourse.group/t/complex-number-multiplication/2173/1 "2025-09-15T18:26:41Z")

</div>

I know that openfhe uses complex number for packing. So let’s say I am doing this opeation

```auto
batch_size = 4
inp = [1+1j, 0+0j, 1+0j]
scale = [2.4+3.2j, 6.2+6j, 8.2+11j]

pt = cc.MakeCKKSPackedPlaintext(inp)
ct = cc.Encrypt(keys.secretKey, pt)

pt_scale = cc.MakeCKKSPackedPlaintext(scale)

res = cc.EvalMult(ct, pt_scale)

ptx = cc.Decrypt(res, keys.secretKey)
ptx.SetLength(batch_size)
ptx.GetCKKSPackedValue()

```

I get the following output

```auto
[2.399+0j, 0j, 8.200+0j]

```

The point is do complex multiplication/operations are not performed? If I want to do complex operation, how to do?

---

<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:** [September 15, 2025, 8:16pm UTC](https://openfhe.discourse.group/t/complex-number-multiplication/2173/2 "2025-09-15T20:16:14Z")

</div>

Check the example [simple-complex-numbers.cpp](https://github.com/openfheorg/openfhe-development/blob/v1.4.0/src/pke/examples/simple-complex-numbers.cpp) in OpenFHE v1.4.0. It shows you how to do that.