added negation operator for FieldMatrix

4 jobs for issue/missing_fmatrix_operator in 20 minutes and 16 seconds (queued for 9 seconds)
Status Name Job ID Coverage
  Test
passed debian:10 clang-6-libcpp-17 #7612

00:20:15

passed debian:10 gcc-8-17 #7611

00:16:09

passed debian:9 gcc-6-14 #7613

00:13:41

passed ubuntu:18.04 clang-6-17 #7614

00:19:02