static double[] toDoubleArray(Cl<Double> l) {
  double[] a = new double[l(l)];
  int i = 0;
  if (a.length != 0) for (double x : l)
    a[i++] = x;
  ret a;
}

ifclass IntBuffer
static double[] toDoubleArray(IntBuffer b) {
  int n = l(b);
  double[] a = new [n];
  for i to n:
    a[i] = b.get(i);
  ret a;
}
endif

meta-for float also as int {
  static double[] toDoubleArray(float... l) {
    double[] a = new[l(l)];
    for (int i = 0; i < a.length; i++)
      a[i] = l[i];
    ret a;
  }
}

ifclass IDoubleBuffer
static double[] toDoubleArray(IDoubleBuffer b) {
  int n = l(b);
  double[] a = new [n];
  for i to n:
    a[i] = b.get(i);
  ret a;
}
endif

Began life as a copy of #1004992