Defining a Step Function: Checking for Accuracy

In summary, the conversation is about defining a step function using a given graph and expressing it in terms of u(t). One person shares their definition of the function while the other points out a potential issue with it and offers their own definition. They also discuss the need to find values for t>=0 and the potential discontinuity at 0.
  • #1
EvLer
458
0
I just want to check if I got this right.
Given this graph, I need to define a step function:
Code:
         |
---------| C
         |
_________|_______________
         |
      -C |_________
         |

So, my definition is: C[-u(t) + u(-t)].
Thanks for checking this.
 
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  • #2
f(x) = {c, x < 0}{-c, x > 0}, f(x) is undef at x = 0, though, |f(0)| = c
 
  • #3
Thanks for reply.

I understand the form of the function, but this is for an engineering class, so we have to express everything in terms of u(t), etc. So, this is what I need for some-one to double check.
And they actually never say that there is a discontinuity at 0, because we have to find values for t >=0 and so on.
 
  • #4
I don't think your definition will work so well. Let's say 0<c, and 0<t<c. What is the value of your function? well [tex]u_c(t)=0 \mbox{ for } t<c \mbox{ and } u_c(-t)=0 \mbox{ for } t<c [/tex] since t will just be negative it will still be less than c. So your function will not work in that case. I just worked from left to right to construct the definiton and came up with
[tex] C[1-2u_c(t)] [/tex]

Which seems to work for all t in R.

Regards
 

FAQ: Defining a Step Function: Checking for Accuracy

What is a step function?

A step function is a mathematical function that takes on a constant value within a specific interval and then changes to another constant value. It is a type of piecewise function that is characterized by a series of horizontal lines.

How is a step function defined?

A step function is defined by specifying the intervals where the function takes on different values. These intervals are usually defined by a set of numbers called "breakpoints" or "cutpoints". The function takes on one value within each interval and changes to another value at the breakpoint.

How do you check for accuracy when defining a step function?

To check for accuracy when defining a step function, you should first plot the function and visually check if the function follows the expected pattern of horizontal lines. Then, you can calculate the function values at the breakpoints and compare them to the expected values. Finally, you can use test points within each interval to see if the function takes on the correct values.

What are some common applications of step functions?

Step functions are commonly used in economics, finance, and engineering to model situations where a value abruptly changes at specific points. They are also used in computer science to represent digital signals and in signal processing to filter out unwanted signals.

Can a step function have an infinite number of breakpoints?

Yes, a step function can have an infinite number of breakpoints. In fact, a step function with an infinite number of breakpoints is known as a Heaviside step function. It is commonly used in physics and engineering to model abrupt changes in voltage or current. However, for practical purposes, step functions are usually defined with a finite number of breakpoints.

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