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[10GBT] Questions on the 12D Mapping source code



Brett,

The C source code map_12dpam12_partition_mex.c appears to have missing
initialization of the *tc and *td variables in lines 76,77,78. Consequently,
I was getting random results when using the code in a C program.

With this initialzation bug fixed, there are still a lot of neighboring
points in the 12D constellation which have a Hamming distance of 18 after
inverse mapping. For example, please run

[TA,TB,TC,TD] = map_12dpam12_partition_mex(0,2,4,3,4,3,4);
TD(3)=0;
[w,x1,x2,y1,y2,z1,z2] = demap_12dpam12_partition_mex(TA,TB,TC,TD );

The result is 1,5,2,4,3,4,3 which differs from the original in 18 bit
positions.

Regards,
Sailesh.
srao@phyten.com

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