Fix warnings with ceil in BTD code (#3518)

* Added static_cast to some real to int conversions

* Fixed typo

1 files changed, 2 insertions, 2 deletions

diff --git a/Source/Diagnostics/BTDiagnostics.cpp b/Source/Diagnostics/BTDiagnostics.cpp
index 510c1b946..90b00a24a 100644
--- a/Source/Diagnostics/BTDiagnostics.cpp
+++ b/Source/Diagnostics/BTDiagnostics.cpp
@@ -135,7 +135,7 @@ void BTDiagnostics::DerivedInitData ()
     const amrex::Real dz_snapshot_grid = dz_lab(dt_boosted_frame, ref_ratio);
     // Need enough buffers so the snapshot length is longer than the lab frame length
     // num_buffers * m_buffer_size * dz_snapshot_grid >= Lz
-    const int num_buffers = ceil(Lz_lab / m_buffer_size / dz_snapshot_grid);
+    const int num_buffers = static_cast<int>(std::ceil(Lz_lab / m_buffer_size / dz_snapshot_grid));
     const int final_snapshot_iteration = m_intervals.GetFinalIteration();
 
     // the final snapshot starts filling when the
@@ -156,7 +156,7 @@ void BTDiagnostics::DerivedInitData ()
     // if j = final snapshot starting step, then we want to solve
     // j dt_boosted_frame >= t_intersect_boost = i * dt_snapshot / gamma / (1+beta)
     // j >= i / gamma / (1+beta) * dt_snapshot / dt_boosted_frame
-    const int final_snapshot_starting_step = ceil(final_snapshot_iteration / warpx.gamma_boost / (1._rt+warpx.beta_boost) * m_dt_snapshots_lab / dt_boosted_frame);
+    const int final_snapshot_starting_step = static_cast<int>(std::ceil(final_snapshot_iteration / warpx.gamma_boost / (1._rt+warpx.beta_boost) * m_dt_snapshots_lab / dt_boosted_frame));
     const int final_snapshot_fill_iteration = final_snapshot_starting_step + num_buffers * m_buffer_size - 1;
     if (final_snapshot_fill_iteration > warpx.maxStep()) {
         std::string warn_string =