How to find values of variables when a value is known (after using curve fitter)?

4 次查看（过去 30 天）
Deepshikha Deo
Deepshikha Deo 2024-2-15
评论： Deepshikha Deo 2024-2-26
I have used curve fitter app for my xyz data. The custom equation I used is :
a0*exp(-(((x-x0)*cos(phi)+(y-y0)*sin(phi))^2/0.5*ax^2) - (((y-y0)*cos(phi)-(x-x0)*sin(phi))^2/0.5*ay^2))
The equation has six unknown variables : a0, ax, ay, phi, x0, and y0. After fitting the equation on the data, the values obtained were as follows
a0 = 2.7451, ax = 8.1356, ay = 10.3918, phi = 4.1032, x0 = 88.3697, and y0 = 22.5765
I wanted to find the values of ax and ay when the value of a0 is 61% of its value (i.e., 1.6745). How can I do so?
Thank you
Regards
  2 个评论
Stephen23
Stephen23 2024-2-15
编辑：Stephen23 2024-2-15
An equation must be equal to something... but you have not told us what that formula is equal to.
Should we assume zero?
Deepshikha Deo
Deepshikha Deo 2024-2-15
编辑：Deepshikha Deo 2024-2-15
The z values are treated as equal to the equation. Thus, in curve fitter toolbox you only need to type equation, i.e., z= f(x,y)= equation
And the x,y,z values are used as inputs

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Drew
Drew 2024-2-21
Assume this is a surface fit z = f(x,y) as in Curve Fitter app. If it is given that a0 = 1.6745, then substitute that into your given custom equation
a0*exp(-(((x-x0)*cos(phi)+(y-y0)*sin(phi))^2/0.5*ax^2) - (((y-y0)*cos(phi)-(x-x0)*sin(phi))^2/0.5*ay^2))
which results in the new custom equation
1.6745*exp(-(((x-x0)*cos(phi)+(y-y0)*sin(phi))^2/0.5*ax^2) - (((y-y0)*cos(phi)-(x-x0)*sin(phi))^2/0.5*ay^2))
Finally, use the new custom equation in the curve fitter app to complete a new surface fit on your data. The new surface fit will solve for values of ax, ay, phi, x0, and y0.
If this answer helps you, please remember to accept the answer.
  1 个评论
Deepshikha Deo
Deepshikha Deo 2024-2-26
Thank you for the answer Drew. After some brainstorming, I also thought the same but after some time I realised I missed an important point. What I want is that the surface should be drawn from the maximum value to its 61 percent fall and the values of ax and ay needs to be found at that point. In this first image, values of ax and ay are found at the dotted line which is above the zero. The image is taken from "https://doi.org/10.1016/j.jclepro.2022.133720".
Here is another example in 2D where the golden region is above zero and the blue line used to represent ax (above 0). The image is taken from "doi:10.3390/a8020082".
So, I want to find the values of ax and ay at 61 percent of its maximum value but it should not be from zero. Any suggestion?

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Get Started with Curve Fitting Toolbox 的更多信息

标签

产品

Community Treasure Hunt

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

Start Hunting!

Translated by