@Override
	public Double argAt(final int index) {
		if (index < 0 || index >= arity()) {
			throw new ArrayIndexOutOfBoundsException(format(
				"Argument index out or range [0, %s): %s", arity(), index
			));
		}

		return _sample[index];
	}
Create a new sample point with the given argument array and result value.

@param sample the arguments of the sample point
@throws IllegalArgumentException if the argument array is empty
@throws NullPointerException if the argument array is {@code null}
jenetics.prog/src/main/java/io/jenetics/prog/regression/DoubleSample.java