how to find y values from smoothing spline curve fit and new x values

2 次查看（过去 30 天）
Ross Hanna
Ross Hanna 2018-2-28
Hi there
First of all, i'm unsure whether this question is sufficiently different enough to warrant a new post, if not, apologies and can the moderator merge the questions please.
As background for what i am doing and what i am trying;
https://uk.mathworks.com/matlabcentral/answers/385121-finding-average-value-of-multiple-y-values-for-a-single-x-value
Essentially, I have a graph from a suspension dynamometer, plotting absolute velocity against force which forms a hysteresis loop (Force Vs Velocity.jpg), and from this data i am trying to create a single, averaged line (Force Vs Average Velocity.jpg).
The issue i am having is that i dont have nicely spaced x data. What i have is non-monotonic data which has repetitions, so the number -27.6 is repeated 4 times, with four different values associated with it. Plotting Time against velocity, you get the graph shown in Time Vs Velocity.JPG.
I have attempted curve fitting Time Vs Velocity with a smoothing spline, which has given me a 1x1 cfit named fit_V. What i am trying to do with this is input values for V, such as -300:0.01:300, then somehow, using the curve fit, output the corresponding Time values that would be needed to create those evenly spaced Velocity values.
i have tried;
Velocity_data = -300:0.01:300
y_ouput = fit_V(Velocity_data ) % evaluates as though Velocity data is x data, not y data
y_ouput = feval(fit_V, Velocity_data) % answers to the order of 1E+14, not <350 mm/s
y_output = interp1(Velocity, Time, Velocity_Data) %unique points error
So put simply, how can you find the Y data from user defined x data using cfit or any other method.
Thanks Ross

请先登录，再回答此问题。

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

Community Treasure Hunt

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

Start Hunting!

Translated by