diff --git a/examples/r_randGMRES.cpp b/examples/r_randGMRES.cpp
index 65e10981..0d3785f0 100644
--- a/examples/r_randGMRES.cpp
+++ b/examples/r_randGMRES.cpp
@@ -19,7 +19,6 @@ using namespace ReSolve::constants;
 int main(int argc, char *argv[])
 {
   // Use the same data types as those you specified in ReSolve build.
-  using index_type = ReSolve::index_type;
   using real_type  = ReSolve::real_type;
   using vector_type = ReSolve::vector::Vector;
 
diff --git a/examples/r_randGMRES_CUDA.cpp b/examples/r_randGMRES_CUDA.cpp
index b93552c0..814ca2d4 100644
--- a/examples/r_randGMRES_CUDA.cpp
+++ b/examples/r_randGMRES_CUDA.cpp
@@ -19,7 +19,6 @@ using namespace ReSolve::constants;
 int main(int argc, char *argv[])
 {
   // Use the same data types as those you specified in ReSolve build.
-  using index_type = ReSolve::index_type;
   using real_type  = ReSolve::real_type;
   using vector_type = ReSolve::vector::Vector;
 
diff --git a/resolve/LinSolverDirectRocSparseILU0.cpp b/resolve/LinSolverDirectRocSparseILU0.cpp
index 54d5a181..f4bc82e1 100644
--- a/resolve/LinSolverDirectRocSparseILU0.cpp
+++ b/resolve/LinSolverDirectRocSparseILU0.cpp
@@ -89,8 +89,6 @@ namespace ReSolve
                                                      &buffer_size_U);
     error_sum += status_rocsparse_;
 
-    size_t buffer_size = std::max(buffer_size_A, std::max(buffer_size_L, buffer_size_U));
-
     // Now analysis
     status_rocsparse_ = rocsparse_dcsrilu0_analysis(workspace_->getRocsparseHandle(), 
                                                     n, 
diff --git a/resolve/LinSolverIterativeRandFGMRES.cpp b/resolve/LinSolverIterativeRandFGMRES.cpp
index 5c4137f3..ad6f03b0 100644
--- a/resolve/LinSolverIterativeRandFGMRES.cpp
+++ b/resolve/LinSolverIterativeRandFGMRES.cpp
@@ -118,15 +118,14 @@ namespace ReSolve
     switch(rand_method_) {
       case cs:
         if(ceil(restart_ * log(n_)) < k_rand_) {
-          //k_rand_ = ceil(restart_ * log(n_));
-          k_rand_ = ceil(restart_ * log(n_));
+          k_rand_ = static_cast<index_type>(std::ceil(restart_ * std::log(static_cast<real_type>(n_))));
         }
         rand_manager_ = new RandSketchingCountSketch();
         //set k and n 
         break;
       case fwht:
         if ( ceil(2.0 * restart_ * log(n_) / log(restart_)) < k_rand_) {
-          k_rand_ = ceil(2.0 * restart_ * log(n_) / log(restart_));
+          k_rand_ = static_cast<index_type>(std::ceil(2.0 * restart_ * std::log(n_) / std::log(restart_)));
         }
         rand_manager_ = new RandSketchingFWHT();
         break;
@@ -134,7 +133,7 @@ namespace ReSolve
         io::Logger::warning() << "Wrong sketching method, setting to default (CountSketch)\n"; 
         rand_method_ = cs;
         if(ceil(restart_ * log(n_)) < k_rand_) {
-          k_rand_ = ceil(restart_ * log(n_));
+          k_rand_ = static_cast<index_type>(std::ceil(restart_ * std::log(n_)));
         }
         rand_manager_ = new RandSketchingCountSketch();
         break;
@@ -194,7 +193,7 @@ namespace ReSolve
     rnorm = 0.0;
     bnorm = vector_handler_->dot(rhs, rhs, memspace_);
     rnorm = vector_handler_->dot(vec_s, vec_s, memspace_);
-    double rnorm_true = vector_handler_->dot(vec_v, vec_v, memspace_);
+    // double rnorm_true = vector_handler_->dot(vec_v, vec_v, memspace_);
     //rnorm = ||V_1||
     rnorm = sqrt(rnorm);
     bnorm = sqrt(bnorm);
diff --git a/resolve/RandSketchingCountSketch.cpp b/resolve/RandSketchingCountSketch.cpp
index 6f9b068b..7ce61550 100644
--- a/resolve/RandSketchingCountSketch.cpp
+++ b/resolve/RandSketchingCountSketch.cpp
@@ -51,8 +51,7 @@ namespace ReSolve
   {
     k_rand_ = k;
     n_ = n;
-    srand(time(NULL)); 
-   // srand(1234); 
+    srand(static_cast<unsigned>(time(nullptr)));
     //allocate labeling scheme vector and move to GPU
 
     h_labels_ = new int[n_];
diff --git a/resolve/RandSketchingFWHT.cpp b/resolve/RandSketchingFWHT.cpp
index 1e8e0442..76e91674 100644
--- a/resolve/RandSketchingFWHT.cpp
+++ b/resolve/RandSketchingFWHT.cpp
@@ -1,7 +1,10 @@
+#include <cmath>
+#include <limits>
+
 #include "RandSketchingFWHT.hpp"
 #include <resolve/MemoryUtils.hpp>
 #include <resolve/vector/Vector.hpp>
-#include <math.h>
+#include <resolve/utilities/logger/Logger.hpp>
 #ifdef RESOLVE_USE_HIP
 #include <resolve/hip/hipKernels.h>
 #endif
@@ -11,6 +14,8 @@
 #include <resolve/RandSketchingFWHT.hpp> 
 namespace ReSolve 
 {
+  using out = io::Logger;
+
   RandSketchingFWHT::RandSketchingFWHT()
   {
     h_seq_ = nullptr;
@@ -62,11 +67,16 @@ namespace ReSolve
     k_rand_ = k;
     n_ = n;
     // pad to the nearest power of 2
-    N_ = pow(2, ceil(log(n_)/log(2)));
-    log2N_ = log2(N_);
-    one_over_k_ = 1.0/sqrt((real_type) k_rand_);
+    real_type N_real = std::pow(2.0, std::ceil(std::log(n_)/std::log(2.0)));
+    if (N_real > static_cast<real_type>(std::numeric_limits<index_type>::max())) {
+      out::error() << "Exceeded numerical limits of index_type ...\n";
+      return 1;
+    }
+    N_ = static_cast<index_type>(N_real);
+    log2N_ = static_cast<index_type>(std::log2(N_real));
+    one_over_k_ = 1.0/std::sqrt(static_cast<real_type>(k_rand_));
 
-    srand(time(NULL)); 
+    srand(static_cast<unsigned>(time(nullptr)));
 
     h_seq_  = new int[N_];
     h_perm_  = new int[k_rand_];
@@ -114,7 +124,7 @@ namespace ReSolve
   //to be fixed, this can be done on the GPU
   int RandSketchingFWHT::reset() // if needed can be reset (like when Krylov method restarts)
   {
-    srand(time(NULL)); 
+    srand(static_cast<unsigned>(time(nullptr)));
 
     int r;
     int temp;