How to write a function code which can convert data strings to signal wave like Sine?

[getuwant]

Suppose we are getting the data strings at recieving end having some values.
Now i need to write a function in C/C++ which can represent the signal waveform of recieved string. Its just like drawing the curve with given values

[RedSon]

what does the string represent? How is the string made up. Give me an example.

[getuwant]

Thaks 4 ur support

Actually string will be a kind of numerical value set.
like
12 34 54 2 3 4 2 1 4 56 7 ........

at recieving end, we want to convert the nos into some waveform.

[RedSon]

what do the numbers represent? The angle? The x,y tuples? If I throw a bag of numbers at you and ask you to make a wave out of it, how are you going to do that if I don't tell you what the number represent?

[getuwant]

Dear sir,
It doesn't matter whether the no's will represent a wave or any other graph.
Likewise if i m getting
x: 12 34 5 3 4 3 2 4 2 44
y: 34 44 5 6 8 5 5 7 5 12

then will that form any shape?
still if u are unable to get me, then please let me know so that i will review my querry again.
thanks

[newb16]

Well, two array of numbers still can be interpreted in diferent ways, but let's suppose that these denote pairs of points {A_i, B_i}
The thing that is not clear to me is "function in C/C++ which can represent the signal waveform". So consider a input set of one pair of x,y = {1,1}
What a function should have as an argument (one floating-point value?) and what should it return for this set for an argument equals, say, 2?

[donbock]

How do you want to represent the signal waveform?

• Are you plotting it on the screen?
• Are you plotting it on the printer?
• Are you plotting it into an image file?
• Are you writing a sequence of values to an A/D chip?
• etc.

Let's take a look at the example input you provided earlier:
12 34 54 2 3 4 2 1 4 56 7 ........

• Do these values represent the y-values for a succession of implied x-values?
• What is the interval between the implied x-values?
• Are you confident that the interval is constant?

[RedSon]

Dear sir,
It doesn't matter whether the no's will represent a wave or any other graph.

I think you have bigger problems to worry about first before you tackle this one.

[jkmyoung]

What I would do is:
1. Store the values.
2. Calculate the correlation of x and y.
If you have a correlation of close to -1 or close to 1, you are looking at more of a linear graph than a wave like graph.

If you have a correlation of close to 0, then you can probably proceed further.

3. Try and figure out the approximate period based on the data. This is more mathematical based, so not well suited to this forum but I'll try to help. Basically you're trying to fit the data so that the maximum areas and minimum areas both have occur in alternating periods. The way to convert this largely depends on what types of variance you expect to see in your data. If you know how you're getting your data, you'll be able to adjust your algorithm accordingly.

Will the rough average of your data will be about the center of your wave line, or are you measuring more the high parts of your data?

To be honest, you haven't given us enough information to proceed further (without resorting to needlessly covering every last case), so if you could give us further information on your data we can help more.

[RedSon]

Likewise if i m getting
x: 12 34 5 3 4 3 2 4 2 44
y: 34 44 5 6 8 5 5 7 5 12

then will that form any shape?
still if u are unable to get me, then please let me know so that i will review my querry again.
thanks

If I plot your (x,y) data pairs assuming that 12,34 and 34,44... etc. are pairs then my best periodic regression fit yields:

2.29055 sin(x) + 4.13434 cos(x) + 14.3573

But the stats on it are not very good, its R2 is only 0.045. You probably want your coefficient of determination to be much higher, maybe in the .90s or so. So as you can see, the data you provide must have meaning attached to it, otherwise you will get garbage.

Remember: Garbage in, garbage out.

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