feat: support modern statistical formula names

CHANGELOG.md

@@ -16,6 +16,9 @@ The release run heads these entries with the version and opens a fresh
 
 ## Unreleased
 
+- Spreadsheet recalculation recognizes STDEV.S, STDEV.P, VAR.S, and VAR.P,
+  including their Excel and LibreOffice compatibility prefixes.
+
 - PDF streams support TIFF predictor samples packed at 1, 2, or 4 bits per
   component. LZW decoding rejects invalid width parameters and dictionary
   growth beyond the format's limit.

src/odr/internal/formula/formula_functions_math.cpp

@@ -306,7 +306,7 @@ template <bool largest> Value kth(const Call &call) {
 
 /// The variance of the numbers, of a sample where @p sample. LibreOffice
 /// takes the mean with `KahanSum` and each deviation with `approxSub`.
-Value variance_of(const Call &call, const bool sample, const bool root) {
+template <bool sample, bool root> Value variance_of(const Call &call) {
   const Collected collected = collect(call);
   if (collected.error.has_value()) {
     return Value{*collected.error};
@@ -662,23 +662,20 @@ constexpr std::array entries{
     FunctionEntry{"SINH", unary<hyperbolic_sine>},
     FunctionEntry{"SMALL", kth<false>},
     FunctionEntry{"SQRT", unary<square_root>},
-    FunctionEntry{
-        "STDEV",
-        [](const Call &call) { return variance_of(call, true, true); }},
-    FunctionEntry{
-        "STDEVP",
-        [](const Call &call) { return variance_of(call, false, true); }},
+    FunctionEntry{"STDEV", variance_of<true, true>},
+    FunctionEntry{"STDEV.P", variance_of<false, true>},
+    FunctionEntry{"STDEV.S", variance_of<true, true>},
+    FunctionEntry{"STDEVP", variance_of<false, true>},
     FunctionEntry{"SUM", sum},
     FunctionEntry{"SUMPRODUCT", sum_product},
     FunctionEntry{"SUMSQ", sum_of_squares},
     FunctionEntry{"TAN", unary<tangent>},
     FunctionEntry{"TANH", unary<hyperbolic_tangent>},
     FunctionEntry{"TRUNC", binary<round_down, 0, true>},
-    FunctionEntry{
-        "VAR", [](const Call &call) { return variance_of(call, true, false); }},
-    FunctionEntry{
-        "VARP",
-        [](const Call &call) { return variance_of(call, false, false); }},
+    FunctionEntry{"VAR", variance_of<true, false>},
+    FunctionEntry{"VAR.P", variance_of<false, false>},
+    FunctionEntry{"VAR.S", variance_of<true, false>},
+    FunctionEntry{"VARP", variance_of<false, false>},
 };
 
 } // namespace

test/src/internal/formula/formula_functions_math_test.cpp

@@ -2,11 +2,13 @@
 
 #include <gtest/gtest.h>
 
+#include <array>
 #include <clocale>
 #include <cmath>
 #include <numbers>
 #include <optional>
 #include <string>
+#include <utility>
 
 using namespace odr::internal::formula;
 using namespace odr::test::formula;
@@ -231,3 +233,18 @@ TEST(FormulaFunctionsMath, the_blank_cells_of_a_whole_column_have_no_answer) {
   // the grid counts the cells past the extent of the sheet
   EXPECT_EQ(xlsx("=COUNTBLANK(A:A)"), std::nullopt);
 }
+
+TEST(FormulaFunctionsMath, modern_statistics_use_the_existing_implementations) {
+  const std::array names{std::pair{"STDEV.S", "STDEV"},
+                         std::pair{"STDEV.P", "STDEVP"},
+                         std::pair{"VAR.S", "VAR"}, std::pair{"VAR.P", "VARP"}};
+  for (const auto &[modern, legacy] : names) {
+    SCOPED_TRACE(modern);
+    EXPECT_EQ(xlsx(std::string("=") + modern + "(2,4,6)"),
+              xlsx(std::string("=") + legacy + "(2,4,6)"));
+    EXPECT_EQ(xlsx(std::string("=_xlfn.") + modern + "(A1:A6)"),
+              xlsx(std::string("=") + legacy + "(A1:A6)"));
+    EXPECT_EQ(ods(std::string("=COM.MICROSOFT.") + modern + "(2;4;6)"),
+              ods(std::string("=") + legacy + "(2;4;6)"));
+  }
+}