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今天小编为大家带来知识打卡（一百一十八）

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内容提要

本期继续学习复刻论文的文章《消费者后悔预期对竞争型再制造供应链权力结构的影响》，上一期中我们已经将三种权力结构的CS函数进行了化简，本期我们将来学习无差异曲线的绘制。

In this issue, we will continue to study the article "The impact of consumer regret expectation on the power structure of competitive remanufacturing supply chain" in the reprinted paper. In the previous issue, we have simplified the CS function of the three power structures. In this issue, we will study the drawing of indifference curve in the future.

本期内容将从思维导图、精读内容和知识补充三部分展开。

In this issue, we will start from three parts: mind map, intensive reading content and knowledge supplement.

思维导图精读内容

首先，我们来看看什么是无差异曲线？本文中的无差异曲线代表一条线上所有的（R,y）各点的组合所带来的CS是相同的线，无差异曲线又可以称为等效用线。无差异曲线是一条向右下方倾斜的线，离坐标原点越远，则效用越大。

First, let's see what is the indifference curve? The undifferentiated curve in this paper represents that the combination of all (R, y) points on a line brings CS to the same line. The undifferentiated curve can also be called the equivalent line. The indifference curve is a line inclined to the right and down. The farther it is from the coordinate origin, the greater the utility.

从化简得公式来看，正常绘制的话我们是将CS绘制成曲面，从绘制得曲面来看，对应到R和y上。

From the simplified formula, we can draw CS as a surface in normal drawing.

但是无差异曲线是二维图像，这里就需要采用绘制等高线的方式绘制无差异曲线，具体如下。

But the indifference curve is a two-dimensional image, so it is necessary to draw the indifference curve by drawing contour lines.

知识补充

等高线绘制，在Mathematical中绘制登高线的函数为ContourPlot，一共有四种类型。

Contour drawing: ContourPlot is used to draw the climbing line in Mathematic. There are four types.

它可以将f函数中的x和y自变量参数分别作坐标轴。我们可以使用此函数绘制完全替代品的无差异曲线，如U(x,y)=2x+3y。

It can use the x and y arguments in the f function as coordinate axes respectively. We can use this function to draw the indifference curve of the complete substitute, such as U (x, y)=2x+3y.

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让我们相约明天，

祝您今天过得开心快乐！

That's it for today's sharing.

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welcome to leave us a message,

Let us meet tomorrow.

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参考资料：谷歌翻译、百度百科，Mathematical软件；

参考文献：

[1]高鹏,杜建国,聂佳佳,陆玉梅. 消费者后悔预期对竞争型再制造供应链权力结构的影响[J]. 中国管理科学,2017,25(01):78-87.

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