EIP-5850 Store real and imaginary parts of complex numbers in the least significant and most significant 16 bytes (respectively) of a bytes32 type

This EIP proposes a natural way for complex numbers to be stored in and retrieved from the bytes32 data-type. It splits the storage space exactly in half and, most importantly, assigns real numbers to the least significant 16 bytes and imaginary numbers to the most significant 16 bytes.

To create a complex number one would use

function cnNew(int128 _Real, int128 _Imag) public pure returns (bytes32){
    bytes32 Imag32 = bytes16(uint128(_Imag));
    bytes32 Real32 = bytes16(uint128(_Real));
    return (Real32>> 128) | Imag32; 

and to convert back

function RealIm(bytes32 _cn)  public pure returns (int128 Real, int128 Imag){
	bytes16[2] memory tmp = [bytes16(0), 0];
	assembly {
	    mstore(tmp, _cn)
	    mstore(add(tmp, 16), _cn)

See Add EIP-5850: Complex Numbers stored in Bytes32 types by genkifs · Pull Request #5850 · ethereum/EIPs · GitHub for discussion

The EIP doesn’t discuss the manipulation of complex numbers when they are in Byte32 form because this is undoubtedly a much larger topic.