LDBL_ULP
long double log1p_ldbl_ulp = LDBL_ULP();
test_tol(log2l, tests[i].x, tests[i].log2x, LDBL_ULP());
test_tol(logl, tests[i].x, tests[i].logex, LDBL_ULP());
test_tol(log10l, tests[i].x, tests[i].log10x, LDBL_ULP());
1.82321556793954626202683007050468762914e-1L, LDBL_ULP());
-2.23143551314209755752742563153765697950e-1L, LDBL_ULP());