如何在MATLAB中为符号变量赋予数字? [英] How can I give a number to a symbolic variable in MATLAB?

问题描述

我尝试使用以下代码在MATLAB中声明一个符号变量:

I try to declare a symbolic variable in MATLAB with this code:

 syms a;

我对此变量进行计算，一切都很好.但是我的问题是，我不知道如何给变量赋一个数字并以数字的形式获得结果.例如，我的代码的答案是

I do my computation on this variable and all thing is fine. But my problem is that, I don't know how can I give a number to variable and get the result as a number. For example the answer of my code is

   answer=exp(-10*a);

例如，我想给"a"赋予40并得到答案

For instance I want to give 40 to "a" and get the answer as

   answer = 
        1.9152e-174

我真的很感谢任何建议.

I really appreciate any suggestion.

推荐答案

使用评估

syms a;
answer = exp(-10*a);

a=40;
eval(answer)

ans =
  1.9152e-174

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