Update testLFSR.cxx

Author: ferdymercury

math/mathcore/test/testLFSR.cxx

@@ -5,12 +5,12 @@
 TEST(LFSR, GenerateSequence)
 {
    // PRBS3
-   std::array<std::uint16_t, 2> taps3 = {2, 3}; // Exponents of the monic polynomial
+   std::array<std::uint16_t, 2> taps3 = {3, 2}; // Exponents of the monic polynomial
    auto prbs3 = ROOT::Math::LFSR::GenerateSequence<3, 2, bool>(std::bitset<3>().flip(), taps3); // Start value all high
    EXPECT_EQ(prbs3, std::vector<bool>({false, false, true, false, true, true, true}));
 
    // PRBS4
-   std::array<std::uint16_t, 2> taps4 = {3, 4}; // Exponents of the monic polynomial
+   std::array<std::uint16_t, 2> taps4 = {4, 3}; // Exponents of the monic polynomial
    auto prbs4 = ROOT::Math::LFSR::GenerateSequence<4, 2, bool>(std::bitset<4>().flip(), taps4); // Start value all high
    EXPECT_EQ(prbs4, std::vector<bool>({false, false, false, true, false, false, true, true, false, true, false, true,
                                        true, true, true}));
@@ -22,5 +22,6 @@ TEST(LFSR, GenerateSequence)
                                        false, true,  false, false, false, false, true, false, false, true,  false,
                                        true,  true,  false, false, true,  true,  true, true,  true}));
 
-   // Exponents of the monic polynomial extracted from Keysight waveform generator manual p. 284
+   // Exponents of the monic polynomial were extracted from
+   // Keysight Trueform Series Operating and Service Guide p. 284-285. More examples in tutorials/math/PRBS.C
 }