diff --git a/src/include/dim.hxx b/src/include/dim.hxx
index 089097a27..4e4453728 100644
--- a/src/include/dim.hxx
+++ b/src/include/dim.hxx
@@ -22,7 +22,8 @@ struct Invar
     return {!InvarX::value, !InvarY::value, !InvarZ::value};
   }
 
-  static bool is_invar(int dim)
+  // TODO c++20 make consteval?
+  static constexpr bool is_invar(int dim)
   {
     switch (dim) {
       case 0: return InvarX::value;
diff --git a/src/include/rng.hxx b/src/include/rng.hxx
index 9b8c7236e..2842c5710 100644
--- a/src/include/rng.hxx
+++ b/src/include/rng.hxx
@@ -59,6 +59,12 @@ struct Uniform
 
   Real get() { return dist(*gen); }
 
+  Real get(Real min_override, Real max_override)
+  {
+    return std::uniform_real_distribution<Real>(min_override,
+                                                max_override)(*gen);
+  }
+
 private:
   detail::GeneratorPtr gen;
   std::uniform_real_distribution<Real> dist;
@@ -81,11 +87,11 @@ struct Normal
   Normal() : Normal(0, 1) {}
 
   Real get() { return dist(*gen); }
-  // FIXME remove me, or make standalone func
-  Real get(Real mean, Real stdev)
+
+  Real get(Real mean_override, Real stdev_override)
   {
     // should be possible to pass params to existing dist
-    return std::normal_distribution<Real>(mean, stdev)(*gen);
+    return std::normal_distribution<Real>(mean_override, stdev_override)(*gen);
   }
 
 private:
diff --git a/src/kg/include/kg/Vec3.h b/src/kg/include/kg/Vec3.h
index aff5ba926..b8cf3362a 100644
--- a/src/kg/include/kg/Vec3.h
+++ b/src/kg/include/kg/Vec3.h
@@ -9,6 +9,7 @@
 #include "cuda_compat.h"
 #include <kg/Macros.h>
 #include <psc/gtensor.h>
+#include "psc_bits.h"
 
 namespace kg
 {
@@ -102,6 +103,72 @@ struct Vec : gt::sarray<T, N>
     return *this;
   }
 
+  KG_INLINE Vec& operator/=(T s)
+  {
+    for (size_t i = 0; i < N; i++) {
+      (*this)[i] /= s;
+    }
+    return *this;
+  }
+
+  KG_INLINE T sum() const
+  {
+    T sum{0};
+    for (size_t i = 0; i < N; i++) {
+      sum += (*this)[i];
+    }
+    return sum;
+  }
+
+  KG_INLINE T prod() const
+  {
+    T prod{1};
+    for (size_t i = 0; i < N; i++) {
+      prod *= (*this)[i];
+    }
+    return prod;
+  }
+
+  KG_INLINE T dot(const Vec& w) const
+  {
+    T sum{0};
+    for (size_t i = 0; i < N; i++) {
+      sum += (*this)[i] * w[i];
+    }
+    return sum;
+  }
+
+  KG_INLINE Vec cross(const Vec& w) const
+  {
+    return {(*this)[1] * w[2] - (*this)[2] * w[1],
+            (*this)[2] * w[0] - (*this)[0] * w[2],
+            (*this)[0] * w[1] - (*this)[1] * w[0]};
+  }
+
+  KG_INLINE T mag2() const { return this->dot(this); }
+
+  KG_INLINE T mag() const { return sqrt(this->mag2()); }
+
+  KG_INLINE T max() const
+  {
+    auto max = (*this)[0];
+    for (size_t i = 1; i < N; i++) {
+      max = std::max(max, (*this)[i]);
+    }
+    return max;
+  }
+
+  KG_INLINE Vec inv() const { return T(1) / *this; }
+
+  KG_INLINE Vec<int, N> fint() const
+  {
+    Vec<int, N> res;
+    for (size_t i = 0; i < N; i++) {
+      res[i] = ::fint((*this)[i]);
+    }
+    return res;
+  }
+
   // conversion to pointer
 
   KG_INLINE operator const T*() const { return this->data(); }
@@ -153,6 +220,24 @@ KG_INLINE Vec<T, N> operator*(T s, const Vec<T, N>& v)
   return res;
 }
 
+template <typename T, std::size_t N>
+KG_INLINE Vec<T, N> operator/(T s, const Vec<T, N>& v)
+{
+  Vec<T, N> res;
+  for (size_t i = 0; i < N; i++) {
+    res[i] = s / v[i];
+  }
+  return res;
+}
+
+template <typename T, std::size_t N>
+KG_INLINE Vec<T, N> operator/(const Vec<T, N>& v, T s)
+{
+  Vec<T, N> res = v;
+  res /= s;
+  return res;
+}
+
 template <typename T, std::size_t N>
 KG_INLINE Vec<T, N> operator/(const Vec<T, N>& v, const Vec<T, N>& w)
 {
diff --git a/src/libpsc/psc_push_particles/push_particles_1vb.hxx b/src/libpsc/psc_push_particles/push_particles_1vb.hxx
index 912ad48ad..18c8ff180 100644
--- a/src/libpsc/psc_push_particles/push_particles_1vb.hxx
+++ b/src/libpsc/psc_push_particles/push_particles_1vb.hxx
@@ -24,7 +24,7 @@ struct PushParticlesVb
   static void push_mprts(Mparticles& mprts, MfieldsState& mflds)
   {
     const auto& grid = mprts.grid();
-    Real3 dxi = Real3{1., 1., 1.} / Real3(grid.domain.dx);
+    Real3 dxi = Real3(grid.domain.dx).inv();
     real_t dq_kind[MAX_NR_KINDS];
     auto& kinds = grid.kinds;
     assert(kinds.size() <= MAX_NR_KINDS);
@@ -60,10 +60,8 @@ struct PushParticlesVb
         auto v = advance.calc_v(prt.u());
         advance.push_x(prt.x(), v);
 
-        Int3 final_index;
-        Real3 final_pos_normalized;
-        find_idx_pos_1st_rel(prt.x(), dxi, final_index, final_pos_normalized,
-                             real_t(0.));
+        Real3 final_pos_normalized = prt.x() * dxi;
+        Int3 final_index = final_pos_normalized.fint();
 
         // CURRENT DENSITY BETWEEN (n+.5)*dt and (n+1.5)*dt
         int lg[3];