07-03-2009 03:59 AM
Hi,
I have a text file which has irradiance value over a day.These values are at certain instant of time . I created a graph from these values that look like an inverted hyperbola.I am attaching the text and vi.If you load the text file and enter following data u will get a graph like i got.
; seperator
30 start
40 number of elements
Now what I want to do is to obtain data from the graph at an interval of ten minutes for 24 hrs and use it in an another vi.
07-03-2009 06:16 AM
This could be a solution but I'm not sure if an 11th order polynomial is the right way to go 😞
You said irradiance, I think sun 🙂
So maybe by skipping the data before 05:00 and after 11:00 you can use a Gaussian fit.
Can't you sample data faster than every hour?
07-05-2009 02:33 PM
07-05-2009 03:14 PM
You asked for an interpolation, right?
That vi interpolates the values in array Xi using a polynomial function, returning values in array Yi.
If you enter in Xi all 10 minutes interval you get all you asked for 🙂
I modified it a bit using the data from the other thread so you can choose which one fits best your needs 🙂
Problem is that you have to choose the correct polynomial order.
This is a nice irradiation curve!
What will happen when some clouds passes over your pyranometer?
Your curve won't be so nice 😞
Hope this helped.
Regards