利用正负法绘制隐函数曲线及运算

Drawing the Curve of Implicit Function ard Calculation using Positive-Negative Algorithm

本文简略介绍了正负法绘制隐函数方程曲线的基本原理及绘图要素，给出非单调曲线的换向规则以及曲线长度、曲线包围区域面积的求法。着重对东曲线弧长算法进行改进以提高精度作了讨论，并用MicrosoftVisualBasic实现通过人机对话窗口输入任意隐函数方程，绘制函数曲线并输出其长度，包围区域面积。

This paper gives a brief introduction to the pronciple of drawing the curve of implicit function by using positive - negative algorithm. The rule of direction - change and the method to calculate the length and the surrounding area of the curve are explained. Because of improvement of the method the precision of compution can be raised. At last a sample program is given, which,developed by MS VB version 4. 0,can analyse the implicit function inputed from the interactive window, and output the curve, its length and surrounding area.