NextDouble
====================

.. js:function:: RandomHelper.NextDouble() 

ソース
^^^^^^

.. code-block:: js

        NextDouble() {
            this.Flag = ! this.Flag;
            if (this.Flag) {
                this.C = Math.sqrt(-2 * Math.log(Math_random()));
                this.Theta = Math_random() * Math.PI * 2;
    
                return this.C * Math.sin(this.Theta);
            }
            else {
                return this.C * Math.cos(this.Theta);
            }
        }