slight tweaks

gridder_cxx.h

@@ -155,7 +155,9 @@ template<typename T> inline T fmodulo (T v1, T v2)
   {
   if (v1>=0)
     return (v1<v2) ? v1 : fmod(v1,v2);
-  T tmp=fmod(v1,v2)+v2;
+  T tmp = v1+v2;
+  if (tmp<0)
+    tmp=fmod(v1,v2)+v2;
   return (tmp==v2) ? T(0) : tmp;
   }
 
@@ -518,14 +520,14 @@ template<typename T> class GridderConfig
         grid.data(), grid.data(), T(1), nthreads);
       }
 
-    inline void getpix(T u_in, T v_in, T &u, T &v, int &iu0, int &iv0) const
+    void getpix(T u_in, T v_in, T &u, T &v, int &iu0, int &iv0) const
       {
       u=fmodulo(u_in*psx, T(1))*nu,
       iu0 = int(u-supp*0.5 + 1 + nu) - nu;
-      if (iu0+supp>nu+nsafe) iu0 = nu+nsafe-supp;
+      iu0 = min<int>(iu0, (nu+nsafe)-supp);
       v=fmodulo(v_in*psy, T(1))*nv;
       iv0 = int(v-supp*0.5 + 1 + nv) - nv;
-      if (iv0+supp>nv+nsafe) iv0 = nv+nsafe-supp;
+      iv0 = min<int>(iv0, (nv+nsafe)-supp);
       }
 
     void apply_wscreen(const const_mav<complex<T>,2> &dirty,
@@ -640,14 +642,11 @@ template<typename T, typename T2=complex<T>> class Helper
       auto y0 = xsupp*(iv0-v);
       for (int i=0; i<supp; ++i)
         {
-        auto x = x0+i*xsupp;
-        kernel[i  ] = beta*sqrt(T(1)-x*x);
-        auto y = y0+i*xsupp;
-        kernel[i+supp] = beta*sqrt(T(1)-y*y);
+        kernel[i  ] = x0+i*xsupp;
+        kernel[i+supp] = y0+i*xsupp;
         }
       for (auto &k : kernel)
-        k = exp(k);
-
+        k = exp(beta*sqrt(T(1)-k*k));
       if ((iu0<bu0) || (iv0<bv0) || (iu0+supp>bu0+su) || (iv0+supp>bv0+sv))
         {
         if (grid_w) { dump(); fill(wbuf.begin(), wbuf.end(), T(0)); }

test.py

@@ -233,11 +233,12 @@ def test_no_correlation(nrow, nchan, epsilon, weight):
 
 
 @pmp('epsilon', [1e-2, 1e-4, 1e-7, 1e-10, 1e-11, 1e-12, 2e-13])
-@pmp('nxdirty', [12, 128])
-@pmp('nydirty', [4, 12, 128])
+@pmp('nxdirty', [2, 12, 128])
+@pmp('nydirty', [2, 4, 12, 128])
 @pmp("nrow", (10, 100))
 @pmp("nchan", (1, 10))
 def test_against_dft(nxdirty, nydirty, epsilon, nchan, nrow):
+    np.random.seed(42)
     bl, conf, idx = _init_gridder(nxdirty, nydirty, epsilon, nchan, nrow)
     ms = np.random.rand(nrow, nchan)-0.5 + 1j*(np.random.rand(nrow, nchan)-0.5)
     vis = bl.ms2vis(ms, idx)