How do you find the zeroes of a discrete function?

In summary, the conversation discussed finding the zeroes of the function y = 40sin(2x) - floor(40sin(2x)) where Y,X \in R. The problem is only equal to zero when 40sin(2x) is an integer, but the distribution of these integers is random and the inverse-floor function is unknown. The suggestion was made to use Newton's method, and the speaker mentioned using an iterated Newton method to speed up the process. The function was encountered in a context of finding a continuous analog for a given discrete function.
  • #1
Frogeyedpeas
80
0
Would Newton's method or some other method work? Consider the following problem:

find the zeroes of the function: y = 40sin(2x) - floor(40sin(2x))

where Y,X [itex]\in[/itex] R

I don't exactly know how to handle this problem. My best insight so far is that it is only equal to zero whenever 40sin(2x) is an integer. But even then the distribution of these integers is quite random and I honestly don't know any inverse-floor function.
 
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  • #2
Frogeyedpeas said:
Would Newton's method or some other method work? Consider the following problem:

find the zeroes of the function: y = 40sin(2x) - floor(40sin(2x))

where Y,X [itex]\in[/itex] R

I don't exactly know how to handle this problem. My best insight so far is that it is only equal to zero whenever 40sin(2x) is an integer. But even then the distribution of these integers is quite random and I honestly don't know any inverse-floor function.
Could you tell us a little more about what class this is from, and what kind of similar problems you may have encountered, and tell us a little about the techniques you're class us covering?
 
  • #3
ehhh not exactly from a class (sorry), and I don't have any sample problems for this thing either. It just kind of came up. My best guess is to use Newton's formula.

I mean Newton's method
 
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  • #4
So this problem i basically the same thing as frac{40sin(2x)} = 0.
 
  • #5
w8 nvm I'm good, I got the method
 
  • #6
So what was the method? Where did the problem come up?
 
  • #7
Well it turns out if you do an iterated Newton method the number works. To speed things up i broke up the function into separate segments defined as linear. The function appeared out of the context of being given a discrete function how do you make a contonuous analog
 

FAQ: How do you find the zeroes of a discrete function?

What are zeroes of a discrete function?

The zeroes of a discrete function are the values of the independent variable that make the dependent variable equal to zero. In other words, they are the x-values where the function crosses the x-axis.

How do you determine the zeroes of a discrete function graphically?

To find the zeroes of a discrete function graphically, plot the function on a graph and look for the points where the graph crosses the x-axis. These points represent the x-values of the zeroes.

How do you find the zeroes of a discrete function algebraically?

To find the zeroes of a discrete function algebraically, set the function equal to zero and solve for the variable. This can be done using various methods such as factoring, the quadratic formula, or the rational root theorem.

Can a discrete function have more than one zero?

Yes, a discrete function can have multiple zeroes. This means there can be multiple x-values that make the function equal to zero.

How do you test the accuracy of the calculated zeroes of a discrete function?

To test the accuracy of the calculated zeroes, plug the values back into the function and see if they result in a value of zero. If they do, then the calculated zeroes are accurate.

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