Best Fit Curve [RESOLVED]

[CVMichael]

I want to make a program that will fix a distorted sound, it is not any type sound, it is a tone (which actually makes things easier)

When the sound is too loud, it will be cut off.
I want to decrease the sound volume, and complete (by approximation) the parts that are missing.

I searched on google for "best fit curve", I have found programs that do this, but not for sounds, and I didn't find any source code.

What I want is to have a function where I give the points that I have (that are valid), and I want it to complete the rest of the points based on the points i'm giving it.

If you look at the attached picture you will have a better idea.
The top wave, is the distorted one, and the bottom, is one where I manually fixed one of the "bumps" of the sound.

the part in between the 2 vertical lines is the part where the function should complete.
I want to give the function a few points that are before the left line, and a few points after the right line.

I also found on the internet formulas to do it, but I'm not that good at math (grade 12 math is the last one I took, in coledge math is not required ), I was hoping that someone might explain to me how to do it in a programming way.

Any idea on how to do this ?
Please help...

Thank You.

[Rassis]

Hi,

A polynomial function of second or perhaps third degree can be approximated by the least squares method. The algorithm is rather complex but I know how to do it in Excel. Does it suit you?

[CVMichael]

Sure, explain to me how it's done ?

Also if you could explain in a way that i may put it in programming, sometimes math formulas are difficult to put in programming.

If i don't understand it, I have a friend that's much better than me in math, most likely he will understand it.

Thanks

[Rassis]

Hi Michael,

It is impossible to explain in this forum how to handle polynomial regression. Please take a look at the attached spreadsheet and these sites:

http://home.ubalt.edu/ntsbarsh/Busin.../PolynoReg.htm
http://www.nlreg.com/
http://www.statsoft.com/textbook/stathome.html

Hope this helps.

I have been to Vancouver a few years ago together with my wife and travelled through British Columbia and Alberta states. It was just marvellous. Nice cities, nice people and spectacular landscapes. You are lucky.

[CVMichael]

Thank you for the links, and the Excel example.

It seems that what I need now is to find out how LINEST is calculated. Once I get the 3 numbers (a & b & c), I can draw the Polinomial Regression.

I looked up on the internet and I can't find anything, I have to code it in Visual Basic, and also in C/C++

In Visual Basic, I can create an Excel object, and just call the LinEst function, but if i do it in C++, I can't, I have to re-invent the wheel, and actually create the LinEst function.

Do you know how LINEST is calculated ?

Thanks

[Rassis]

I am sorry but I don´t know how the LINEST function is calculated. I only use it in MS-Excel. I like maths (mainly stats) and I use it a lot in my professional life, but I am not well acquainted with coding.

I am afraid you will have to "reivent the wheel" starting with the maths on the polinomial regression, unless you get help from other peers in the mean time.

Hope you manage.

[yrwyddfa]

try:

http://www.vbforums.com/showthread.p...ht=polynomials

[CVMichael]

Thank you yrwyddfa, that link solved my problem
Rassis, thank you to you also, for helping me...

Finally, I got it to work, I had to do a little more than what is in the link provided by yrwyddfa.

Now I can fix sounds (Tones) that are over-amplified up to 6 TIMES, and it will still fix it back.