      for (SizeT j = 0; j < n; ++j) { //nb output points
        vres = &(res[ncontiguous * j ]);
        x = xx[j]; if (x<0) x=0; if (x>n1-1) x=n1-1;
        y = yy[j]; if (y<0) y=0; if (y>n2-1) y=n2-1;
        z = zz[j]; if (z<0) z=0; if (z>n3-1) z=n3-1;

        ix = floor(x); 
        xi[0] = ix;
        xi[1] = ix + 1;
        //make in range
        if (xi[1] < 0) xi[1] = 0; else if (xi[1] > n1 - 1) xi[1] = n1 - 1;
        dx = (x - xi[0]); umdx=1-dx;

        iy = floor(y);
        yi[0] = iy;
        yi[1] = iy + 1;
        //make in range
        if (yi[1] < 0) yi[1] = 0; else if (yi[1] > n2 - 1) yi[1] = n2 - 1;
        dy = (y - yi[0]); umdy=1-dy;

        iz = floor(z);
        zi[0] = iz;
        zi[1] = iz + 1;
        //make in range
        if (zi[1] < 0) zi[1] = 0; else if (zi[1] > n3 - 1) zi[1] = n3 - 1;
        dz = (z - zi[0]); umdz=1-dz;

        vx0y0z0 = &( array[ncontiguous * ( zi[0] * n1n2 + yi[0] * n1 + xi[0])] );
        vx1y0z0 = &( array[ncontiguous * ( zi[0] * n1n2 + yi[0] * n1 + xi[1])] );
        vx0y1z0 = &( array[ncontiguous * ( zi[0] * n1n2 + yi[1] * n1 + xi[0])] );
        vx1y1z0 = &( array[ncontiguous * ( zi[0] * n1n2 + yi[1] * n1 + xi[1])] );
        vx0y0z1 = &( array[ncontiguous * ( zi[1] * n1n2 + yi[0] * n1 + xi[0])] );
        vx1y0z1 = &( array[ncontiguous * ( zi[1] * n1n2 + yi[0] * n1 + xi[1])] );
        vx0y1z1 = &( array[ncontiguous * ( zi[1] * n1n2 + yi[1] * n1 + xi[0])] );
        vx1y1z1 = &( array[ncontiguous * ( zi[1] * n1n2 + yi[1] * n1 + xi[1])] );
        for (SizeT i = 0; i < ncontiguous; ++i) {
          double y0z0=umdx*vx0y0z0[i]+dx*vx1y0z0[i];
          double y1z0=umdx*vx0y1z0[i]+dx*vx1y1z0[i];
          double y0z1=umdx*vx0y0z1[i]+dx*vx1y0z1[i];
          double y1z1=umdx*vx0y1z1[i]+dx*vx1y1z1[i];
          double   z0=umdy*y0z0+dy*y1z0;
          double   z1=umdy*y0z1+dy*y1z1;
          vres[i] = umdz*z0+dz*z1; 
        }
      }