How to plot this function?

Question

John 2014-12-24

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https://ww2.mathworks.cn/matlabcentral/answers/168022-how-to-plot-this-function

评论： Star Strider 2014-12-24

I have a function that is "vectorized". I did that because I wanted to have one such function for each value of the parameter "a":

clc;
clear all;
tic;
a=[1/2,1/3,1/4];
p = @(x) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) ;

I want to have the three plots (one for each value of "a") in the same figure. However, I am having trouble isolating each function for plotting. For instance, I expected that:

p1 = @(x) p(x,1,1)

would represent one of functions, but it doesn't. My other attempts have also failed. How can I get the desired result?

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Answer 1

Star Strider 2014-12-24

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/168022-how-to-plot-this-function#answer_163276

编辑：Star Strider 2014-12-24

在 MATLAB Online 中打开

The easiest way is to pass ‘a’ as a parameter as well:

a=[1/2,1/3,1/4];
p = @(x,a) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) ;
p1 = p(x,a(1));

Not that within the function, ‘a’ is whatever you want it to be. If you define it as a parameter, it will not pick up the value of ‘a’ from the workspace.

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John 2014-12-24

编辑：John 2014-12-24

在 MATLAB Online 中打开

You've already helped a lot. But if I don't put "@(x)"I get an error message:

clc;
clear all;
tic;
a=[1/2,1/3,1/4];
p = @(x,a) 1/3.*(exp(x.^(a))-1)./(exp(x.^(a))+1) ;
p1 = p(x,a(1));
%p2 = p1(x);

Gives me:

Undefined function or variable 'x'.

Error in Untitled2 (line 9) p1 = p(x,a(1));

Star Strider 2014-12-24

在 MATLAB Online 中打开

Thank you. I do my best!

Now I understand what you’re doing. If you only want it as a function of ‘x’, you have to specify it as you did:

p1 = @(x) p(x,a(1));

It all depends on how you want to call your function. There are at least a few ways to do it correctly, so choose the one that works best for you in your application. I chose the way I usually do it in my two versions of the plot call.

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