Georgi Guninski on Sat, 18 Jul 2026 08:13:57 +0200


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Does matrix rank makes sense modulo composite $n$?


Both pari and sage fail to compute the rank of matrix modulo composite $n$:
? M=Mod(1,4)*[2,2;2,2]
? matrank(M)
  ***   at top-level: matrank(M)
  ***                 ^----------
  *** matrank: impossible inverse in Fl_inv: Mod(2, 4).

Does matrix rank makes sense modulo composite $n$?