Finding Equation of a Graph: Tips & Tricks

[DjDukes]

I am wondering how to go about finding the equation of a graph of the following form. I understand how to make a graph oscillate but not in this way.

 

[Bill Simpson]

Please, don't anyone just blurt out what the answer is. Let him figure it out.

Hint: Of all the math operations you have ever seen, can you think of one where it grows up to a certain point and then suddenly drops back to the starting value and does this over and over again? Think until you remember that one. Now you might not have ever thought about plotting that, but plot it now and see what it looks like. This will not look exactly like what you have above. So what do you remember about Math 100 that would tell you how to make little changes until you get it to look like what you have above.

 

[DjDukes]

Please, don't anyone just blurt out what the answer is. Let him figure it out.

Hint: Of all the math operations you have ever seen, can you think of one where it grows up to a certain point and then suddenly drops back to the starting value and does this over and over again? Think until you remember that one. Now you might not have ever thought about plotting that, but plot it now and see what it looks like. This will not look exactly like what you have above. So what do you remember about Math 100 that would tell you how to make little changes until you get it to look like what you have above.

No I can't think of one hence why I asked. I am just looking for a straight answer so I can analyse my data not learn mathematics since I am not a mathematician or trying to be one. This isn't for any sort of homework or something if that's why your being cryptic.



I forgot to clarify in the 1st post i just noticed. The graph actually only goes so high. and only drops so far. It is also linear in shape. The highest point is 12 the lowest is 10.7 and the drops are at regular intervals.

 

[Bill Simpson]

The Mod function, which means the remainder after division, looks a lot like what you want. You provided information on the vertical boundaries but not how often it repeats. So I'll guess that 12-((x+.65)mod 1.3) might be what you are looking for.

To try to explain mod 1.3 to you,
2.6=2*1.3+0 so 2.6 mod 1.3=0
2.7=2*1.3+0.1 so 2.7 mod 1.3=0.1
etc.
So in that equation above, you pick any value for x, add .65, either use division or subtraction to remove as many multiples of 1.3 as possible until the result is less than 1.3 but greater than zero and 12-your result will be what you want to plot on a graph.

Here is a graph of that for you
http://www.wolframalpha.com/input/?i=graph+12-((x+.65)+mod+1.3)
Gently adjust the constants to get it closer to what you need. Or tell me the position of the upper left and lower right corners of anyone of your diagonal lines and I'll give you a tweaked equation for your plot.

Or if you need some other way of describing this then try to tell me how you need this done and I'll see what I can do.

 

[DjDukes]

yes that is exactly what I was looking for now to figure out how to apply this to the other graph I have to hopefully get some results! Thanks for the help.