如何学习和使用mathematica（知识打卡12）

如何学习和使用mathematica（知识打卡12）In the last issue we have conducted practical exercises related to matrix but short-term learning is difficult to remember for a long time so we should constantly review and apply it in practice; In this issue we need to further consolidate the knowledge of variables and related contents of user-defined functions and show their application in specific problems through practical examples.由此引出了

分享知识、传播快乐、增长见闻、留下美好，大家好，这里是Leanringyard学院。今天小编将继续为大家带来Mathematica入门教程系列文章，今天的主题就是：Mathematica学习9。

Share knowledge spread happiness increase knowledge and leave beauty. Hello everyone this is leanringyard college. In today's and later articles Xiaobian will continue to bring you a series of Mathematica introductory tutorials. Today's topic is: getting started with Mathematica tutorial 9.

内容提要✦

上一期，我们已经进行了矩阵相关的实际操作演练，但短暂的学习很难长久的被记住，所以我们要不断的复习且实际运用；在本期了，我们需要来进一步巩固有关变量的知识，以及自定义函数相关内容，并通过实际的例子，来展现其在具体问题中的应用。

In the last issue we have conducted practical exercises related to matrix but short-term learning is difficult to remember for a long time so we should constantly review and apply it in practice; In this issue we need to further consolidate the knowledge of variables and related contents of user-defined functions and show their application in specific problems through practical examples.

变量✦

变量是数学名词，从名字来理解就是可以变化的量，一般使用字母或者拉丁字母来代表，但它不可以参与到实际的计算中去，除非为变量赋予真是的数值，简言之，变量就相当于一个某种特定值的保留器。比如x 2=y，这里的x就是自变量，y为因变量，它现在只能表达一个等式关系，要进行结果计算，就需要我们为自变量x进行赋值。

由此引出了变量赋值的问题，前面我们知道为变量赋值使用“=”，那怎样在实际问题种运用了？接下来救我们一起来操作一下吧!

In the last issue we have conducted practical exercises related to matrix but short-term learning is difficult to remember for a long time so we should constantly review and apply it in practice; In this issue we need to further consolidate the knowledge of variables and related contents of user-defined functions and show their application in specific problems through practical examples.

Variable is a mathematical noun. It is a variable quantity understood from the name. It is generally represented by letters or Latin letters but it can not participate in the actual calculation unless the variable is given a true value. In short the variable is equivalent to a retainer of a specific value. For example x 2 = y where x is the independent variable and Y is the dependent variable. Now it can only express an equality relationship. To calculate the result we need to assign a value to the independent variable x.

This leads to the problem of variable assignment. We know that "=" is used for variable assignment. How can it be used in practical problems? Next let's operate it together!

变量赋值运用✦

1、当x=10 计算x x^2 12:

1. When x = 10 calculate x x ^ 2 12:

2、x=1 y=2 z=3 计算x y z^3:

3、假设x={a b c d}，将第三个值c进行赋值，令其等于10：

3. Assuming x = {a B C D} assign the third value C to make it equal to 10:

4.继续第三题，假设y=4 x 求y:

4. Continue with question 3 assuming y = 4 X find y:

5，清除x值，并令x=a b 求x b的值：

5. Clear the value of X and make x = a B to find the value of X B:

自定义函数✦

首先，看看Mathematica中对自定义函数的描述：

First let's take a look at the description of custom functions in Mathematica

​举一个简单的例子表示 我们定义一个函数：f(x)为x^2的展开式，既x=(a b) f(x)=a^2 ab b^2，在mathematica中就表示为：

This leads to the problem of variable assignment. We know that "=" is used for variable assignment. How can it be used in practical problems? Next let's operate it together!

As a simple example we define a function: F (x) is the expansion of x ^ 2 that is x = (a b) f (x) = a ^ 2 AB B ^ 2 which is expressed in Mathematica as:

​我们还可以用另外一种表达方式：

we can use another way:

​这里的/.和—>表示在表达式中进行替代操作。

Here / And - > represent substitution operations in expressions.

END✦

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参考资料：谷歌翻译、百度百科，Mathematica软件

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