
theorem
  for M being Matrix of COMPLEX holds M + 0_Cx(len M,width M) = M
proof
  let M be Matrix of COMPLEX;
A1: len M=len COMPLEX2Field M & width M=width COMPLEX2Field M;
  M + 0_Cx(len M,width M) = M +(- 0_Cx(len M,width M)) by MATRIX_4:9
    .= Field2COMPLEX ((COMPLEX2Field M)-(COMPLEX2Field M-COMPLEX2Field M))
  by MATRIX_4:3
    .= M by A1,MATRIX_4:11;
  hence thesis;
end;
