Add logit test set

test/Jamfile.v2

@@ -591,6 +591,7 @@ test-suite special_fun :
    [ run test_fibonacci.cpp /boost/test//boost_unit_test_framework ]
    [ run test_prime.cpp /boost/test//boost_unit_test_framework ]
    [ run test_logistic_sigmoid.cpp ]
+   [ run test_logit.cpp ]
 ;
 
 test-suite distribution_tests :

test/test_logit.cpp

@@ -0,0 +1,87 @@
+// Copyright Matt Borland 2025.
+// Use, modification and distribution are subject to the
+// Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/math/special_functions/logit.hpp>
+#include <boost/multiprecision/cpp_bin_float.hpp>
+#include "math_unit_test.hpp"
+#include <array>
+#include <cfloat>
+
+#pragma STDC FENV_ACCESS ON
+
+template <typename RealType>
+void test()
+{
+    const std::array<RealType, 5> x_values = {
+        0.01,
+        0.24,
+        0.5,
+        0.75,
+        0.995,
+    };
+    const std::array<RealType, 5> y_values = {
+        RealType{-4.595119850134589926852434051810180709116687969582916078687956376405},
+        RealType{-1.15267950993838545919655007350715126451438856911612411268258589327840479},
+        RealType{0},
+        RealType{1.09861228866810969139524523692252570464749055782274945173469433363749429},
+        RealType{5.2933048247244923954101212918685372018911052805694724989064609879440992}
+    };
+
+    for (std::size_t i = 0; i < x_values.size(); ++i)
+    {
+        const RealType test_value {boost::math::logit(x_values[i])};
+
+        BOOST_MATH_IF_CONSTEXPR (std::is_arithmetic<RealType>::value)
+        {
+            CHECK_ULP_CLOSE(test_value, y_values[i], 5);
+        }
+        else
+        {
+            CHECK_MOLLIFIED_CLOSE(test_value, y_values[i], 1e-15);
+        }
+
+        bool fe {false};
+        if (std::fetestexcept(FE_OVERFLOW))
+        {
+            fe = true;
+            std::cerr << "FE_OVERFLOW" << std::endl;
+        }
+        if (std::fetestexcept(FE_UNDERFLOW))
+        {
+            fe = true;
+            std::cerr << "FE_UNDERFLOW" << std::endl;
+        }
+        if (std::fetestexcept(FE_DIVBYZERO))
+        {
+            fe = true;
+            std::cerr << "FE_DIVBYZERO" << std::endl;
+        }
+        if (std::fetestexcept(FE_INVALID))
+        {
+            fe = true;
+            std::cerr << "FE_INVALID" << std::endl;
+        }
+
+        CHECK_EQUAL(fe, false);
+    }
+}
+
+int main()
+{
+    std::feclearexcept(FE_ALL_EXCEPT);
+    test<float>();
+
+    std::feclearexcept(FE_ALL_EXCEPT);
+    test<double>();
+
+    std::feclearexcept(FE_ALL_EXCEPT);
+    test<long double>();
+
+    std::feclearexcept(FE_ALL_EXCEPT);
+    test<boost::multiprecision::cpp_bin_float_quad>();
+
+    return boost::math::test::report_errors();
+}