Z4cow: initial lapse to W

Z4cow/schedule.ccl

@@ -143,6 +143,13 @@ SCHEDULE Z4cow_Initial2 IN Z4cow_InitialGroup AFTER Z4cow_Initial1
   WRITES: Gam_tilde(interior)
 } "Convert ADM to Z4c variables, part 2"
 
+SCHEDULE Z4cow_InitialLapse IN Z4cow_InitialGroup AFTER Z4cow_Initial2
+{
+  LANG: C
+  READS: W(interior)
+  WRITES: alphaG(interior)
+} "Set initial lapse"
+
 SCHEDULE Z4cow_Enforce IN Z4cow_PostStepGroup
 {
   LANG: C

Z4cow/src/initiallapse.cxx

@@ -0,0 +1,29 @@
+#include <loop_device.hxx>
+#include <simd.hxx>
+
+#include <cctk.h>
+#include <cctk_Arguments.h>
+
+namespace Z4cow {
+using namespace Arith;
+using namespace Loop;
+
+extern "C" void Z4cow_InitialLapse(CCTK_ARGUMENTS) {
+  DECLARE_CCTK_ARGUMENTSX_Z4cow_InitialLapse;
+
+  const array<int, dim> indextype = {0, 0, 0};
+  const GF3D2layout layout1(cctkGH, indextype);
+  typedef simd<CCTK_REAL> vreal;
+  typedef simdl<CCTK_REAL> vbool;
+  constexpr size_t vsize = tuple_size_v<vreal>;
+
+  grid.loop_int_device<0, 0, 0, vsize>(
+      grid.nghostzones, [=] ARITH_DEVICE(const PointDesc &p) ARITH_INLINE {
+        const vbool mask = mask_for_loop_tail<vbool>(p.i, p.imax);
+        const GF3D2index index1(layout1, p.I);
+        // Store
+        alphaG.store(mask, index1, W(mask, index1));
+      });
+}
+
+} // namespace Z4cow

Z4cow/src/make.code.defn

@@ -7,6 +7,7 @@ SRCS = \
 	enforce.cxx	\
 	initial1.cxx \
 	initial2.cxx \
+	initiallapse.cxx \
 	newradx.cxx \
 	rhs.cxx