diff --git a/Test/matBasic_real_test.cpp b/Test/matBasic_real_test.cpp
index 2a35497..b9ca1b3 100644
--- a/Test/matBasic_real_test.cpp
+++ b/Test/matBasic_real_test.cpp
@@ -79,6 +79,27 @@ i_real_matrix genTestMatrixb(const std::size_t nAnt, const std::size_t nEq)
     return resMat;
 }
 
+
+bool CheckIdentity(const i_real_matrix& mat)
+{
+    const float EPS = 1.0e-20;
+
+    double sumErrSqr = 0;
+    for (std::size_t r = 0; r < mat.size(); r++)
+    {
+        const i_real_vector& row = mat[r];
+        for (std::size_t c = 0; c < row.size(); c++)
+        {
+            i_float_t diff = c == r ? row[c] - i_float_t(1.0) : row[c];
+            sumErrSqr = diff * diff;
+        }
+    }
+    
+    return sumErrSqr < EPS;
+}
+
+
+
 void pinvTest(bool doLargeMatTest = true)
 {
     std::cout << "\n\n******************** pinv test ********************\n\n";
@@ -106,7 +127,13 @@ void pinvTest(bool doLargeMatTest = true)
         {-6.0, 3.0, 9.0, 1.0}};
     std::cout << "rank(matC) = " << rank(matC) << "\n";
     showMatrix(matC, "matC");
-    showMatrix(inv(matC), "inv(matC)");
+
+    i_real_matrix invMatC = inv(matC);
+    showMatrix(invMatC, "inv(matC)");
+    bool isIdentity = CheckIdentity(matMul(matC, invMatC));
+    if (!isIdentity)
+        std::cout << "not identity";
+
     showMatrix(pinv(matC), "pinv(matC)");
     showMatrix(pinv2(matC), "pinv2(matC)");
     std::cout << "\n\n";
diff --git a/Test/matBasic_testUtil.hpp b/Test/matBasic_testUtil.hpp
index 12d327d..c8ece44 100644
--- a/Test/matBasic_testUtil.hpp
+++ b/Test/matBasic_testUtil.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <iostream>
-#include <sys/time.h> // Performance test timer
+#include <chrono>
 
 
 class TestTimer
@@ -13,7 +13,7 @@ class TestTimer
     void tic()
     {
         m_running = true;
-        gettimeofday(&m_time_start, NULL);
+        m_time_start = std::chrono::steady_clock::now();
     }
 
     double toc(const char *printInfo = nullptr)
@@ -21,9 +21,11 @@ class TestTimer
         double res = 0.0;
         if (m_running)
         {
-            gettimeofday(&m_time_end, NULL);
+            m_time_end = std::chrono::steady_clock::now();
             m_running = false;
-            res = static_cast<double>(m_time_end.tv_sec - m_time_start.tv_sec) + static_cast<double>(m_time_end.tv_usec - m_time_start.tv_usec) / 1000000.0;
+            auto time_diff = m_time_end - m_time_start;
+            auto microSecs = std::chrono::duration_cast<std::chrono::microseconds>(time_diff).count();
+            res = static_cast<double>(microSecs) / 1.0e6;
             if (nullptr != printInfo)
             {
                 std::cout << "Time elapsed - " << printInfo << ": ";
@@ -45,15 +47,8 @@ class TestTimer
     }
 
 private:
-    struct timeval m_time_start
-    {
-        0, 0
-    };
-
-    struct timeval m_time_end
-    {
-        0, 0
-    };
+    std::chrono::steady_clock::time_point m_time_start;
+    std::chrono::steady_clock::time_point m_time_end;
 
     bool m_running{false};
 };