Unexpected Matlab Expression ?

2017 9 11
1 个回答
回答已采纳
更新时间：2017 9 11
2 次查看（30 天）

1 个投票

I am new to coding and am unsure why my code does not work it says "Unexpected MATLAB expression" for the 3 in my code.
This is my code E(x)= [-1 1] 3 . * exp (1) . ^ ((-x)./4)
Any help is appreciated

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Jose Marques
Jose Marques 2017-9-11
Should be something between [-1 1] and 3.* ? What this represents?
Jose Marques
Jose Marques 2017-9-11
Maybe it is better to explain what the expression means.
Natalie Brehaut
Natalie Brehaut 2017-9-11
it is supposed to be an envelope to another function, I have tried to add .* in between but that comes up as unexpected MATLAB Operator
Natalie Brehaut
Natalie Brehaut 2017-9-11
I am supposed to code the function E(x)= plus or minus 3e^(-x/4)

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Jose Marques
Jose Marques 2017-9-11

0 个投票

Natalie, try this:
E= [-1 1] * 3 *( exp (1) .^ ((-x)/4))
E will be a matrix 1x2 that first element is positive value and second will be the negative value

7 个评论
显示 5更早的评论 隐藏 5更早的评论

Natalie Brehaut
Natalie Brehaut 2017-9-11
When that is put in it says that the Matrix dimensions must agree
Jose Marques
Jose Marques 2017-9-11
Are you using the matrix E after that? Post you intire code; thus, we can be helpfull
Natalie Brehaut
Natalie Brehaut 2017-9-11
编辑：Natalie Brehaut 2017-9-11
Trial>> x= 1: 0.1 : 10; Trial>> y= 3 . * exp (1) .^ ((-x)/4) . * sin (2 . * x) y= 3 . * exp (1) .^ ((-x)/4) . * sin (2 . * x) ↑ Error: Unexpected MATLAB operator.
Trial>> E= [-1 1] * 3 *( exp (1) .^ ((-x)/4)) Error using * Inner matrix dimensions must agree.
I am just very lost in what is wrong with my codes
Jose Marques
Jose Marques 2017-9-11
A tip: you must use .* to element wise multiplication: https://www.mathworks.com/help/matlab/ref/times.html
Jose Marques
Jose Marques 2017-9-11
Natalie, have you ever use the for loop? Do you just wanna two values for E?
x=1:0.1:10;
for i=1:size(x,2)
y(i) = 3 * exp (1) .^ ((-x(i))/4) * sin (2 * x(i));
E= [-1 1] * 3 *( exp (1) .^ ((-x(i))/4));
end
plot(y)
Natalie Brehaut
Natalie Brehaut 2017-9-11
THAT WORKED THANK YOU SO MUCH

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by