code: public void build(Point3d[] points, int nump) throws IllegalArgumentException {
          if (nump < 4) {
              throw new IllegalArgumentException("Less than four input points specified");
          }
          if (points.length < nump) {
              throw new IllegalArgumentException("Point array too small for specified number of points");
          }
          initBuffers(nump);
          setPoints(points, nump);
          buildHull();
      }
docs: Constructs the convex hull of a set of points.
  
  @param points
  input points
  @param nump
  number of input points
  @throws IllegalArgumentException
  the number of input points is less than four or greater then
  the length of <code>points</code>, or the points appear to be
  coincident, colinear, or coplanar.