Get a smooth line

[Richard]

I want to get a chart like this picture..(the line is smooth)


But I can't do it.
If I use smoothing function, I'll get this chart...


Is there any way to get the chart like the first picture?
Please tell me, it's vary important to me.

[Narcís]

Hi Richard,

Have you tried increasing function's Factor property? If this doesn't help, can you please post a simple example project or a code snippet we can run "as-is" to reproduce the problem here?

Thanks in advance.

[Richard]

Hi Narcís

I've tried increasing function's factor property, but it didn't work.
This is an example that I made:https://docs.google.com/leaf?id=0B__elU ... NmEx&hl=en
The datasource of line2 is from line1, function's factor property is 40, and interpolate is true (because the line have to cross every points).
But it is still not straight between the second point and the third point.
I don't know what I can do. I am new...please tell me how to get the chart (like the picture that I post first time).

[Narcís]

Hi Richard,

I've tried increasing function's factor property, but it didn't work.
This is an example that I made:https://docs.google.com/leaf?id=0B__elU ... NmEx&hl=en
The datasource of line2 is from line1, function's factor property is 40, and interpolate is true (because the line have to cross every points).
But it is still not straight between the second point and the third point.

Thanks for the information but I don't have access to the google document you linked.

I don't know what I can do. I am new...please tell me how to get the chart (like the picture that I post first time).

TeeChart uses the sandard algorithm for computing natural cubic splines described in Wikipedia.

The cubic spline function from Wikipedia:



is similar to SpLine.cs, line 350, for example:

Code: Select all

					double mix=(dist<1) ? (4.0/6.0)-(dist*dist)+(0.5*dist*dist*dist) : (2-dist)*(2-dist)*(2-dist)/6;

Clamping or not is what we call interpolated.

Do you know which algorithm the image you attached uses or any other more accurate Spline calculation algorithm, be it polynomiol or not?

Thanks in advance!

[Richard]

Hi Narcís,

I've reset the link.
https://docs.google.com/leaf?id=0B__elU ... NmEx&hl=en

I think it doesn't have any algorithm.
User key in coordinates then get a chart that I want.
For example, user key in 4 points (0,10), (1,5), (2,5), (3,1).
If I use smoothing function, then the line will like a wave between point2 and point3.
But I want that is straight between point2 and point3.

Thanks for your help.

[Narcís]

Hi Richard,

Which charting package plots your data points the way you'd like them to be plotted? Which tool did you use to plot the chart in the first image you posted?

Thanks in advance.

[Richard]

Hi Narcís,

It is from "GEOFLTR MFC Application".
Can teecahrt get the chart?

Thanks your help again.

[Narcís]

Hi Richard,

It is from "GEOFLTR MFC Application".

Could you please give us more detailed information or a URL about this application?

Can teecahrt get the chart?

I'm afraid not unless Smoothing function is enhanced to calculate Splines as you request. That's why we need to know which is the algorithm used for such calculations.

Thanks in advance.