您正在关注此问题

您将在关注的内容源中看到更新。
您可能会收到电子邮件，具体取决于您的通信预设项。

finding the two coordinates

1 次查看（过去 30 天）

显示更早的评论

Babu Sankhi 2020-10-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates

⋮

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates

评论： Babu Sankhi 2020-10-4

采纳的回答： Matt J

new.pdf

Hi all,

I have a plot from experimental data. I want to find the two values of x that corresponds to y=0. Basically, I want to find the coordinates A and B ( in both coordinates y=0) in the file attached below. I tried by using " find (x==0)" but it gave me blank. Can you please help how can I find them?

Thank you

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Matt J 2020-10-2

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#answer_503812

⋮

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#answer_503812

在 MATLAB Online 中打开

fzero(@(x)interp1(A,x), [1,numel(A)])

13 个评论
显示 11更早的评论隐藏 11更早的评论

Babu Sankhi 2020-10-2

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034095

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034095

编辑：Babu Sankhi 2020-10-2

I am sorry it did not work? It gave me the error like this:

Error using fzero (line 246)

FZERO cannot continue because user-supplied function_handle ==> @(x)interp1(0,x) failed with the error below.

Interpolation requires at least two sample points in each dimension.

Error in Hallode (line 42)

fzero(@(x)interp1(0,x), [1,numel(0)])

Perhaps I donot have any function. I just have a plot (y versus x) from my experimental data. I need to find the the points on the plots at which y becomes 0. There are two coordinates corresponding to this. Can you help me more?

Matt J 2020-10-2

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034143

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034143

编辑：Matt J 2020-10-2

在 MATLAB Online 中打开

It looks like instead of passing in a vector A, you passed in the scalar 0. To see how it's suposed to work, suppose we have, for example,

A=[-ones(1,10), -.25,0.5, +ones(1,10)]; plot(A,'x-');

Now, do the thing:

>> fzero(@(x)interp1(A,x), [1,numel(A)])
ans =
   11.3333

Babu Sankhi 2020-10-2

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034176

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034176

编辑：Babu Sankhi 2020-10-2

在 MATLAB Online 中打开

It gave me error like that . ( BTW I have to get two values of x at y=0). Can you please help me more?

>> fzero(@(x)interp1(y,x), [1,numel(y)])
Error using fzero (line 290)
The function values at the interval endpoints must differ in sign.
 

thank you

Matt J 2020-10-2

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034203

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034203

BTW I have to get two values of x at y=0

Just apply the method twice, once to each curve.

Babu Sankhi 2020-10-2

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034392

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034392

编辑：Babu Sankhi 2020-10-2

I tried that way as well. But it did nt give the right one!

Moreover I should get the two values of X from single plot can we do that?

can you please help me ?

Matt J 2020-10-3

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034440

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034440

编辑：Matt J 2020-10-3

In what way is the answer wrong? You realize that a=60.46 is the index at which the root occurs, correct?

Babu Sankhi 2020-10-3

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034446

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034446

编辑：Babu Sankhi 2020-10-3

Rather than this , interpo1( y,x,0) worked well. BTW thank you. But still I am needing idea if Y=0 does not have unique value( in my case there are two values of X at Y=0 and i need to get both) . It would great if you can help me in this regard.

Matt J 2020-10-3

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034485

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1034485

编辑：Matt J 2020-10-3

I told you before. You should split the data into two separate curves.

Babu Sankhi 2020-10-4

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035346

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035346

try.txt

I tried by splitting the data and tried to find the x values for certain y value by using interpolation. It always gave me the error as seen clear in the figure attached below. I have also attached the one set of data tha I used. Can you please help me to figure out the problem?

Matt J 2020-10-4

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035352

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035352

编辑：Matt J 2020-10-4

It is not terribly useful to see an image of your code. It is best to present the code in text form so that we can copy, paste and run it. Also, this data does not have any locations where Y=0. Are you trying to find the X for which Y=-4.54?

Babu Sankhi 2020-10-4

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035358

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035358

编辑：Babu Sankhi 2020-10-4

在 MATLAB Online 中打开

figure(3);
dt=importdata('try.txt');
x=dt(:,1);
y=dt(:,2);
plot(x,y,'r--o')
xlabel('X');
ylabel('Y');
set(gca,'Fontsize',18)
xvalue =interp1(y,x,-4.54);% x value at y=-4.54

I have pasted codes above,

Yes I am trying to find the X for which Y=-4.54. Can you help me more?

Thank you

Matt J 2020-10-4

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035517

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1035517

编辑：Matt J 2020-10-4

在 MATLAB Online 中打开

xvalue = fzero(  @(xq)interp1(x,y+4.54,xq) ,  [min(x),max(x)] )% x value at y=-4.54

Babu Sankhi 2020-10-4

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1036150

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603391-finding-the-two-coordinates#comment_1036150

Thank you ,

It worked now.

请先登录，再进行评论。

另请参阅

类别

MATLAB Mathematics Interpolation Interpolation of 2-D Selections in 3-D Grids

在 Help Center 和 File Exchange 中查找有关 Interpolation of 2-D Selections in 3-D Grids 的更多信息

Community Treasure Hunt

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

Start Hunting!

发生错误

由于页面发生更改，无法完成操作。请重新加载页面以查看其更新后的状态。

Translated by

选择网站

选择网站以获取翻译的可用内容，以及查看当地活动和优惠。根据您的位置，我们建议您选择：。

(English)
(Deutsch)
(Français)

（简体中文）
(English)

您也可以从以下列表中选择网站：

如何获得最佳网站性能

选择中国网站（中文或英文）以获得最佳网站性能。其他 MathWorks 国家/地区网站并未针对您所在位置的访问进行优化。

美洲

América Latina (Español)
Canada (English)
United States (English)

欧洲

Belgium (English)
Denmark (English)
Deutschland (Deutsch)
España (Español)
Finland (English)
France (Français)
Ireland (English)
Italia (Italiano)
Luxembourg (English)

Netherlands (English)
Norway (English)
Österreich (Deutsch)
Portugal (English)
Sweden (English)
Switzerland
United Kingdom(English)

亚太

Australia (English)
India (English)
New Zealand (English)
中国
- 简体中文Chinese
- English
日本Japanese (日本語)
한국Korean (한국어)

联系您当地的办事处

finding the two coordinates

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

13 个评论
显示 11更早的评论隐藏 11更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

finding the two coordinates

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

13 个评论 显示 11更早的评论隐藏 11更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

13 个评论
显示 11更早的评论隐藏 11更早的评论