[MaL] Use full precision for Eigen matrix output (fmt/spdlog)

MathLib/FormattingUtils.cpp

+/**
+ * \file
+ * \copyright
+ * Copyright (c) 2012-2024, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#include "FormattingUtils.h"
+
+namespace MathLib
+{
+Eigen::IOFormat const EigenIOFormat::full_precision{
+    Eigen::FullPrecision, 0, " ", "\n", "", "", "", "", ' '};
+}  // namespace MathLib

MathLib/FormattingUtils.h

@@ -15,8 +15,21 @@
 #include <Eigen/Core>
 #include <concepts>
 
+namespace MathLib
+{
+struct EigenIOFormat
+{
+    static const Eigen::IOFormat full_precision;
+};
+}  // namespace MathLib
+
 template <typename T>
 requires std::derived_from<T, Eigen::DenseBase<T>>
 struct fmt::formatter<T> : fmt::ostream_formatter
 {
+    auto format(T const& value, fmt::format_context& ctx) const
+    {
+        return fmt::ostream_formatter::format(
+            value.format(MathLib::EigenIOFormat::full_precision), ctx);
+    }
 };