What is Step function: Definition and 142 Discussions

In mathematics, a function on the real numbers is called a step function (or staircase function) if it can be written as a finite linear combination of indicator functions of intervals. Informally speaking, a step function is a piecewise constant function having only finitely many pieces.

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  1. C

    Laplace transform of step function

    this isn't homework, this is just general knowledge and i can't figure it out.. please help, thx Find the Laplace transform of the given function: f(t) = { 0 t<2, (t-2)^2 t>=2 I tried working it out and this is where i get stuck f(t) = (t-2)^2 * u(t-2) I am not sure if I got the...
  2. C

    Step Function (heaviside) laplace xform

    Hi, I currently have this problem to solve and I can't seem to figure it out it goes like this Find the Laplace transform of the given function: f(t) = { 0 t<2, (t-2)^2 t>=2 I tried working it out and this is where i get stuck f(t) = (t-2)^2 * u(t-2) I am not sure if I got...
  3. U

    Trying to integrate a summation of a unit step function.

    Homework Statement Define I(x)= I( x - x_n ) = { 0 , when x < x_n { 1, when x >= x_n. Let f be the monotone function on [0,1] defined by f(x) = \sum_{n=1}^{\infty} \frac{1}{2^n} I ( x - x_n) where x_n = \frac {n}{n+1} , n \in \mathbb{N} . Find \int_0^1 f(x) dx ...
  4. S

    MATLAB Creating a unit step function in Matlab

    Hi Guys, I am trying to create a basic unit step function in Matlab that needs to be in the range of" -5 <= x <= 5 I need this to be done via a function and not piece together using different intervals and it needs to show the whole -5 to 5 interval. I am just beginning in Matlab and am...
  5. U

    Complex Riemann-Stieltjes integral with a step function for integrator

    Hello all. In my book (Mathematical Analysis by Apostol), the author states and proves the following theorem for real (i.e. f and alpha are functions from [a,b] to R) Riemann-Stieltjes integrals: Assume c\in(a,b) and \alpha is such that \alpha(a)=\alpha(x) when a\leq x<c, and...
  6. G

    Step Function: Numerical Precision Matters

    Hi, Friends How to numerically do with step function? I mean, this function is very sensitive to the precision. For example, f(x) is a step function. When x is greater than some very small positive number, \delta, the numerical answer is 1, which agrees with the expected value. But when x <...
  7. K

    Can the unit step function express e^t between 0 and 2?

    Homework Statement Express f(t) = e^t, 0<t<2, using the unit step function 2. The attempt at a solution e^t*u(t-2) is an expression for a graph of the function that is zero until t=2. My guess is e^t*u(t+2)
  8. T

    Help with DE and UNIT STEP FUNCTION

    I'm not sure how to solve a differential equation with unit step function, for example: x'' + 2x' + x = 10t*u(t), where x(0)=1 and x'(0)=0 Do I just ignore the u(t) and solve it regularly by normal integration?
  9. M

    Heaviside (Unit step function) question

    Homework Statement The function f(t) is defined for t>=0 by f(t) = 1 for 0<= t <= 1 , t-2 for 1 <=t <= 2 and 0 for t >2 Express f(t) in terms of the Heaviside function and hence or otherwise find L(f(t)), the Laplace transform of f(t) Homework Equations The Attempt at a...
  10. P

    Dirac delta function and Heaviside step function

    [SOLVED] Dirac delta function and Heaviside step function In Levine's Quantum Chemistry textbook the Heaviside step function is defined as: H(x-a)=1,x>a H(x-a)=0,x<a H(x-a)=\frac{1}{2},x=a Dirac delta function is: \delta (x-a)=dH(x-a) / dx Now, the integral: \int...
  11. J

    Unit Step Function Homework: Solve f(t) for t = -1

    Homework Statement I'm having a bit of difficulty understanding the unit step function For example f(t) = 6u(-t) + 6u(t+1) - 3u(t+2) t = -1 Homework Equations The Attempt at a Solution If t = -1 then the way I would do the problem is say that if u(t) returns a negative number...
  12. D

    Sketch Signal: (t-4)[u(t-2)-u(t-4)]

    The question says to sketch the signal (t-4)[u(t-2)-u(t-4)]. I know that the inner part is a delay of two and a delay of four, but I don't know what to do with the (t-4)...does it have anything to do with the slope?
  13. J

    Inverse Laplace Transform - Step Function?

    Given... (2s^{2}+1)e^{-s} ------------------ (s - 1)(s^{2} + 4s + 5) Find the inverse Laplace Transform. I am unsure where to start and am just looking for a little direction, not an answer. From past experience, I am assuming I will have to rewrite this in another form...perhaps by...
  14. A

    Compute the Z-transform of a^{-n} and step function

    Homework Statement Compute the Z-transform of x[n] = (0.5)^{-n} * u[n-1] And find the ROC (Region of Convergence) Homework Equations Z-Transform for discrete time x(z) = \sum_{n=0}^\infty x[n] * z^{-n} The Attempt at a Solution To solve this, I used the definition of...
  15. B

    Proof of Integrability for Bounded and Integrable Function

    Homework Statement Let f be a function that is integrable on [a,b] and bounded by 0 \leq f(x)\leq M for some M. Prove that f^{2} is also integrable on this interval. Homework Equations We've done many problems with step functions s(x)\leq f(x) \leq t(x), where s(x) and t(x) are...
  16. D

    Representing Unit Step Function in MATLAB

    How do you represent a unit step in MATLAB as ONE function, y , for example. I know only how to graph multiple vectors on top of the same graph (using hold on/off) and getting the graph output, but i can't represent it as a function itself. Any ideas?
  17. P

    Integration with a step function?

    Integration with a step function?? Homework Statement How do you go about integrating a function that has parameters "x" and "delta" where "delta" is a step function of "x" (delta is 1 for x>0, 0.5 for x=0, and 0 for x<0)?? I don't remember doing anything like this in any of my math...
  18. A

    What is the laplace transform of u(-t)?

    Homework Statement Find the laplace transform of u(-t) Homework Equations The Attempt at a Solution For u(t), the laplace transform of it is 1/s, basically taking the integral of e^-st from 0 to infinity. In this case, since the unit step function approaches from the negative...
  19. T

    Laplace Transform - Step Function

    Homework Statement What is the Laplace transform of f(t) = t^2 - 18 for 0 < t < 3 and f(t) = (t-3)^2 for t>3?Homework Equations Laplace Transforms 3. Work Using Heaviside/step function, made equation into: f(t) = t^2 - 18 + u(t-3)( (t-3)^2 - (t^2-18) ) Then, using Laplace transforms...
  20. T

    Is a Unit Step Function or Series the Solution to this Equation?

    Homework Statement I have an equation that has the following values at different intervals: It is: r when 0<x<2Pi r - (1)d when 2Pi<x<4Pi r - (2)d when 4Pi<x<6Pi And so on. I want to find a function that encompasses this whole function. Unit functions / discontinuity functions are fine; as...
  21. E

    How can i sketch the graph of a step function

    could you give me the method of sketching the graph of a step function here is an example: N(t)=25(2||t+2/2||-t) thanks a lot for your help
  22. O

    Writing down the step function

    Hi there, I'm stuck on getting my step function set up. the function is: f(t)= 0, t<0 (a/b)*t, 0<t<b a, t>b where a and b are just constants. Here's my step function of the first two intervals...the first one I didn't do anything to it since it's zero, so I got...
  23. C

    How can we simplify the integral of a step function with a derivative?

    Suppose U(x) is the step function and \delta(x) is its derivative. Find \int^{6}_{-2}(x^{2}-8)\delta(x)\dx . I know \delta(x) = 0 for all x except x = 0 . So at x = 0 v(x) = - 8 . After this step, how do we get \int_{-2}^{2}(x^{2}-8)\delta(x)\dx +\int^{6}_{2}(x^{2}-8)\delta(x)\dx =...
  24. S

    Help with integrating step function

    Dear All, I have a moderate knowledge of mathematics and need help on an integration question. How would I go about integrating a step function: H(K - Z), when the integral is from K=Z to infinity. Please advise, your help would be much appreciated. Suz
  25. T

    What Does the Heaviside Step Function Formula Represent?

    f(x) = <x-a>^1 - <x-2a>^1 - a<x-3a>^0 this is a diagram of heaviside step function.does anybody has any website regarding this materials so that i can get to learn such as why is it power of one and power of zero plssss thanx very much
  26. G

    Step Function / Heavenside help

    Is this the proper way to write the Heavenside function for the following conditions: g(t) = t if t <= 8pi 8pi if t > 8pi Heavenside: g(t) = t + (8pi - t)*U(t-8pi)
  27. S

    Convolution with time shifted step function.

    How do you go about convolving when x(t) = u(t-1)? Can you just make the limits of integration 1 to t instead of 0 to t?
  28. electronic engineer

    Calculating Fourier Transform of Unit Step Function

    how can I calculate the Fourier transform for unit step function: v(t)=1 where 0=<t<+infinity v(t)=0 otherwise I applied the general definition relation for FT: v(w)=integral(v(t)*e^-jwt) ; - infinity<t<+infinity but i had v(w)=infinity due to the term infinity-displaced e^(+jwt)...
  29. Cyrus

    Cable System Step Function Analysis

    Cable System - Step Function Hi, I want to do an experiment using two dissimilar ropes in my basement and see if I can produce some results using a rope analysis. Here’s the set up. I want to tie a light rope to a heavy rope, and be able to characterize the curvature the system takes on. I...
  30. S

    Combining Fourier Series for Step Function: $\phi_{n} = \sin(nx)$

    Find the FOurier Series in terms of \phi_{n} = \sin(nx) of the step function f(x) = 0 for 0 \leq x \leq \frac{1}{2} \pi [/tex] f(x) =1 for [itex] \frac{1}{2} \pi < x \leq \pi now i have no problem finding the series for each branch. But how would i combine them? for the 0 to 1/2 pi...
  31. S

    Finding the Fourier Series of a Step Function

    Find the Fourier Series in terms of \phi_{n} = \sin{nx} of the step function f(x) = 0 for 0 \leq x \leq \frac{1}{2} \pi = 1 for \frac{1}{2} \pi < x \leq \pi Solution Fourier Series is \Sigma c_{n} \phi_{n} and for hte interval for x between 0 and 1/2 pi c_{n} =...
  32. H

    Learning Integration with unit step function like u(x - a)

    hello maths experts is the following true? http://img9.imageshack.us/img9/4596/int15oe.jpg graphically, this is how i view it http://img9.imageshack.us/img9/179/int28ut.jpg
  33. E

    What is the effect of step functions on slope changes?

    heaviside or step function I don't quite understand how to add step functions and would like to get that down before this one class begins. Does anyone know a good tutorial or a helpful site or a book with answers? Thank you.
  34. P

    Need help with Impulse function and unit step function at singularity

    I have some trouble wrapping my head around singularity One of assignment question is to show that the unit function is not defined at 0. To do that, I need to show \lim_{\Delta\to0}[u_{\Delta}(t)\delta(t)]=0 \lim_{\Delta\to0}[u_{\Delta}(t)\delta_{\Delta}(t)]=\frac{1}{2}\delta(t)...
  35. A

    Discussing the Near Step Function for γ=0.4823241136337762

    I would like to invite comment to the near step function below. \Mvariable{step(x)}=\frac{{e^{-\frac{\gamma }{{x^2}}}}}{{\sqrt{1-\frac{{e^{-\frac{\gamma }{{x^2}}}}}{{x^2}}}}} the above function evaluates to nearly 1 for |x|>1 and nearly zero for |x|<0.3 for gamma =...
  36. E

    How does a step function affect the output voltage of an ideal OP-AMP?

    I am given an ideal OP-AMP like this (R-resistor, Cap-capacitor): ____+Cap-_ | | ___R____|__|\______|_____ + | -|/ + | V in | V out - | | | |_________|______________ - and V in is...
  37. S

    Unit Step Function and Laplace Transforms

    Hey I was wondering if someone would check my work on this problem: Note: {\cal L} = Laplace {\cal U} = Unit Step Function {\cal L} \{ \cos(2t) \,\,\, {\cal U} (t - \pi)\} =e^{-\pi s} {\cal L} \{ \cos(2(t + \pi)) \} =e^{-\pi s} {\cal L} \{ \cos(2t + 2\pi) \} =e^{-\pi s}...
  38. E

    Defining a Step Function: Checking for Accuracy

    I just want to check if I got this right. Given this graph, I need to define a step function: | ---------| C | _________|_______________ | -C |_________ | So, my definition is: C[-u(t) + u(-t)]. Thanks for checking this.
  39. S

    Understanding Heaviside Step Function - Explained with Examples

    Heaviside? HELP hey there peeps, could u guys help me out with heaviside step function..cu zi don't understand anything bout how it works and how to apply to a particular problem... could u guys explain in detail how to solve the next equations using heaviside: exp[-2s] F(s)=...
  40. S

    Integrability of a step function

    Let f (x) = 1 if 2<=x<4 2 if x =4 -3, if 4<x<=7 Prove that this function is integrable on [2,7], state its value and prove that it is what you say it is. Obviously integral of f from [2,7] is -7. but its proof and the integrability have me and my friends snagged. Suggestions anyone? SO...
  41. S

    Proof of the integrability of a step function

    My second course in analysis and i have a problem which i can't understand Let f (x) = 1 if 2<=x<4 2 if x =4 -3, if 4<x<=7 Prove that this function is integrable on [2,7], state its value and prove that it is what you say it is. Obviously integral of f from [2,7]...
  42. W

    Derivative of unit step function

    [SOLVED] Derivative of unit step function How does one do this, for example x= e^(-3t)u(t-4); how do you get x' ??
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