BMat8::one(size_t)

Author: hivert

include/bmat8.hpp

@@ -291,7 +291,19 @@ class BMat8 {
     //! Returns the identity BMat8
     //!
     //! This method returns the 8 x 8 BMat8 with 1s on the main diagonal.
-    static BMat8 one() { return BMat8(0x8040201008040201); }
+    static BMat8 one(size_t dim = 8) {
+        HPCOMBI_ASSERT(dim <= 8);
+        static std::array<uint64_t, 9> const ones = {0x0000000000000000,
+                                                     0x8000000000000000,
+                                                     0x8040000000000000,
+                                                     0x8040200000000000,
+                                                     0x8040201000000000,
+                                                     0x8040201008000000,
+                                                     0x8040201008040000,
+                                                     0x8040201008040200,
+                                                     0x8040201008040201};
+        return BMat8(ones[dim]);
+    }
 
     //! Returns a random BMat8
     //!

tests/test_bmat8.cpp

@@ -101,6 +101,29 @@ struct Fix {
 //****************************************************************************//
 BOOST_AUTO_TEST_SUITE(BMat8_test)
 //****************************************************************************//
+BOOST_FIXTURE_TEST_CASE(BMat8_one, Fix) {
+    BOOST_TEST(BMat8::one(0) == zero);
+    BOOST_TEST(BMat8::one(2) == BMat8(
+                   {{1, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 1, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0}}));
+    BOOST_TEST(BMat8::one(5) == BMat8(
+                   {{1, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 1, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 1, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 1, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 1, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0},
+                    {0, 0, 0, 0, 0, 0, 0, 0}}));
+    BOOST_TEST(BMat8::one(8) == BMat8::one());
+}
+
 BOOST_FIXTURE_TEST_CASE(BMat8_transpose, Fix) {
     BOOST_TEST(zero.transpose() == zero);
     BOOST_TEST(bm2.transpose() == bm2t);