/usr/include/madness/external/muParser/ is in libmadness-dev 0.10-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/madness/external/muParser/muParser.h
/usr/include/madness/external/muParser/muParserBase.h
/usr/include/madness/external/muParser/muParserBytecode.h
/usr/include/madness/external/muParser/muParserCallback.h
/usr/include/madness/external/muParser/muParserDLL.h
/usr/include/madness/external/muParser/muParserDef.h
/usr/include/madness/external/muParser/muParserError.h
/usr/include/madness/external/muParser/muParserFixes.h
/usr/include/madness/external/muParser/muParserInt.h
/usr/include/madness/external/muParser/muParserStack.h
/usr/include/madness/external/muParser/muParserTest.h
/usr/include/madness/external/muParser/muParserToken.h
/usr/include/madness/external/muParser/muParserTokenReader.h