/usr/include/boost/multiprecision/detail/ is in libboost1.58-dev 1.58.0+dfsg-5ubuntu3.
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/usr/include/boost/multiprecision/detail/big_lanczos.hpp
/usr/include/boost/multiprecision/detail/bitscan.hpp
/usr/include/boost/multiprecision/detail/default_ops.hpp
/usr/include/boost/multiprecision/detail/digits.hpp
/usr/include/boost/multiprecision/detail/dynamic_array.hpp
/usr/include/boost/multiprecision/detail/et_ops.hpp
/usr/include/boost/multiprecision/detail/float_string_cvt.hpp
/usr/include/boost/multiprecision/detail/functions/
/usr/include/boost/multiprecision/detail/functions/constants.hpp
/usr/include/boost/multiprecision/detail/functions/pow.hpp
/usr/include/boost/multiprecision/detail/functions/trig.hpp
/usr/include/boost/multiprecision/detail/generic_interconvert.hpp
/usr/include/boost/multiprecision/detail/integer_ops.hpp
/usr/include/boost/multiprecision/detail/no_et_ops.hpp
/usr/include/boost/multiprecision/detail/number_base.hpp
/usr/include/boost/multiprecision/detail/number_compare.hpp
/usr/include/boost/multiprecision/detail/rebind.hpp
/usr/include/boost/multiprecision/detail/ublas_interop.hpp
/usr/include/boost/multiprecision/detail/utype_helper.hpp