LabVIEW
How to plot y=mx+c
Once you calculate your m and c, just use your x values to calculate the y values based on the line you calculated. That will give you and array of x values and an array of y values to put into your graph.
Oh, and you can simplify your code A LOT by letting LabVIEW work on the arrays directly. There is actually no reason here to use Index Array.
The main problem is that your document is wrong. The sums actually need to be taken from i=0 to i=N-1 (The document says i=1 to i=N-1, which is incorrect).
You need to make the VI scalable, so the code works no matter how many points there are in the input arrays. You don't want to write different subVIs for each array size, right? Also remember that "index array" is resizable, so would only need one instance to get all elements.
As Tim said, you can get N for each array by using "array size" (you might even include error handling and return an error if the X and Y arrays are of different size or if both are size=0, for example.). The rest of the code can be done by operating directly on arrays.
Yes, as you pointed out, there is a linear fit built into LabVIEW. I would still place it on the diagram, just to see if your own code returns about the same results. Two opinions are better than one! (most likely they will not be identical to the last bit, but that is to be expected).
Before saving an example VI, you should fill the values from the document into the x and y arrays and make the values the default so you don't need to enter anything next time you work on the VI.
And, yes follow your advisors suggestion and build the code into a subVI. I would recommend to use the same connector pattern as the built-in linear fit subVI, just leave out the stuff that you don't use.
Here's one possibility how the flat code (not subVI yet) would look like. Study it in detail and make sure you understand every single part of it, then do your own. Good luck!
SafetyCarrot wrote:As a side note, have you any ideas as to how to make the line of best fit a curve? As in polynomial regression.
Well, yes. However, earlier you said that:
@SafetyCarrot wrote:
I realise LabView already has the ability to plot it for me, but my assignment requires me to do it myself with my own code.
Your linear fit IS already a polynomial regression (order=1), so all you need is add higher orders. Are you now allowed to use the built-in functions?
Just replace the part where you get the line coefficients with "general polynomial fit". I would also recommend to generate the fit curve with a denser series of x-values over a slightly wider range in order to better show the curvature. Simply create a new x-ramp (e.g. using "ramp pattern" and, together with the best fit polynomial coefficients, use "polynomial evluation" to generate the new curve for display.
Now make the code scalable and make the polynomial order a control. Now you can do linear fit or any order of polynomial fit all with exactly the same code! 😄
See how far you get....
