/**
# High-order interpolation

Higher-order interpolation can be more appealing altough it is
approx. 15 times more expensive than regular `interpolate()` in 3D.

![Cell-centered colouring](thi3d/sn.png)

![quarticly interpolated colouring](thi3d/si.png)
 */
#include "grid/octree.h"
#include "higher-order.h"

#define interpolate interpolate_5
#define quartic linear
#include "utils.h"

scalar s[];

int main() {
  L0 = 4;
  origin (-L0/2.05, -L0/2.5, -L0/3.);
  init_grid (8);
  foreach()
    s[] = exp(-sq(x) - sq(y) - sq(z));
  boundary({s});
  output_ppm (s, file = "sn.png", n = 380, max = 1);
  output_ppm (s, file = "si.png", n = 380, quartic = true, max = 1);
}