计算变螺距螺杆虚线方程及其圆柱面展开线方程。输入初始螺距、终止螺距、螺线直径、螺杆长度，便可得到螺线圈数，螺线方程、螺线长度、展开线方程及其长度-Calculation equation and the variable pitch cylindrical screw dashed line equation to start. Enter the initial pitch, the termination pitch, spiral diameter, screw length, will