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C++ API

Function File: phi = ls_intersect (phi1, phi2)
Function File: phi = ls_intersect (phi, ...)

Calculate a level-set function for the intersection of the sets described by the argument level-set functions.

See also: ls_complement, ls_union, ls_setdiff, ls_setxor, intersect.

Demonstration 1

The following code

  n = 100;
  x = linspace (-7, 7, n);
  [XX, YY] = meshgrid (x, x);

  phi1 = (XX - 2 * cos (7/6 * pi)).^2 + (YY - 2 * sin (7/6 * pi)).^2 - 3^2;
  phi2 = (XX - 2 * cos (11/6 * pi)).^2 + (YY - 2 * sin (11/6 * pi)).^2 - 3^2;
  phi3 = XX.^2 + (YY - 2).^2 - 3^2;
  phi = ls_intersect (phi1, phi2, phi3);

  figure ();
  subplot (1, 2, 1);
  hold ("on");
  contour (XX, YY, phi1, [0, 0], "k");
  contour (XX, YY, phi2, [0, 0], "k");
  contour (XX, YY, phi3, [0, 0], "k");
  hold ("off");
  axis ("equal");

  subplot (1, 2, 2);
  hold ("on");
  imagesc (x, x, phi);
  set (gca (), "ydir", "normal");
  ls_sign_colourmap ();
  contour (XX, YY, phi, [0, 0], "k");
  hold ("off");
  axis ("equal");

Produces the following figure

Figure 1

Package: level-set