Simplify partition functions

src/partfun/CMakeLists.txt

@@ -8,7 +8,7 @@ target_include_directories(partfun_generator PRIVATE ${ARTS_SOURCE_DIR}/src)
 
 file(GLOB_RECURSE partfun_xml_files LIST_DIRECTORIES FALSE RELATIVE ${ARTS_PARTFUN_DATA_PATH} "*.xml")
 set(partfun_cpp_files ${partfun_xml_files})
-list(TRANSFORM partfun_cpp_files REPLACE ".xml" ".cc")
+list(TRANSFORM partfun_cpp_files REPLACE ".xml" ".cpp")
 list(TRANSFORM partfun_xml_files PREPEND "${ARTS_PARTFUN_DATA_PATH}/")
 
 # Generate auto_partfun.h for the ARTS interface

src/partfun/data/Ar-8.cpp

@@ -0,0 +1,32 @@
+//! auto-generated file
+
+#include <configtypes.h>
+
+#include <array>
+
+inline constexpr std::array<Numeric, 4> coeffs{ 1, 0, 0, 0 };
+
+
+Numeric /Users/richard/Work/arts/src/partfun/data/Ar8(Numeric T) noexcept {
+  Numeric result = coeffs[0];
+  Numeric TN     = 1.0;
+
+  for (int i = 1; i < 4; i++) {
+    TN     *= T;
+    result += TN * c;
+  }
+
+  return result;
+}
+
+Numeric d/Users/richard/Work/arts/src/partfun/data/Ar8(Numeric T) noexcept {
+  Numeric result = coeffs[1];
+  Numeric TN     = 1.0;
+
+  for (int i = 2; i < 4; i++) {
+    TN     *= T;
+    result += static_cast<Numeric>(i) * TN * coeffs[i];
+  }
+
+  return result;
+}