Compilation.md

@@ -75,6 +75,7 @@ Edit `complex_mumps_seq/include/petscconf.h` and set
 #undef PETSC_HAVE_UNISTD_H
 #undef PETSC_HAVE_GETPAGESIZE
 #undef PETSC_HAVE_SLEEP
+#undef PETSC_HAVE_IEEEFP_H
 ```
 
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