Questions tagged [piecewise-continuity]

For use when asking questions about piecewise continuous functions, their properties, or the functional branch itself.

Piecewise continuous functions are functions that have the following properties:

  1. The left and right hand limits exist everywhere on the function.

  2. The function is discontinuous for at least one point.

A piecewise continuous function can always be expressed as two functions f + g where f is continuous and g is a piecewise constant constant function.

g is sometimes referred to as the jump series or jump component of the piecewise continuous function. g can only be determined up to some constant c. The formula for finding g is:

$$g(x) = \sum_{n=0}^{JC(x)} (\lim_{a -> JL(n)^+} f(a) - \lim_{a -> JL(n)^-} f(a))$$

Where, JC(x) is the function counting the number of jump discontinuities between $0$ and x, and JL(x) is the discrete function returning the x coordinate of the X'th discontinuity. JC returns a negative count for values of negative x.

Another important operation involving piece-wise continuous functions are two alternative calculus operators, implied by the following:

  1. The indefinite integral "area function" always exists for piece-wise continuous functions, yet the anti-derivative doesn't always exist.

  2. There is no anti-indefinite integral such that the indefinite integral returns the original function, or some analogue fully defined for all $x \in R$

The result is two operators: the implied integral and the implied derivative which fulfill 1 and 2. The implied derivative is nothing more than the one sided derivative limit which is hardly useful or noteworthy. The implied integral on the other hand, has a much deeper change and is defined as a form similar to that of symbolic integration, but where any "symbol" of the form "$\lfloor f(x) \rfloor$" is held fixed and held fixed in the same manner that y is held fixed when integrating the multivariate function f(x,y) with respect to x. The implied integral will vary by piece wise constant functions of x, rather than the usual constants normal integration varies by.

The first fundamental theorem of implied calculus states:

Any integral of f is equal to the implied integral of f minus the jump series of the implied integral of f.

In this way, many integrals can be changed into a problem of finding the jump series.

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Is any algebraic operation between two piecewise constant functions guaranteed to return a piecewise constant function?

Let there be two piece-wise constant functions $f(x)$ and $g(x)$. Is the function composition $h(f(x),g(x))$ always going to be a piece-wise constant function? I believe it is. Nothing would indicate otherwise, in my opinion, but I cannot be sure.
user64742
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Multiplying a piecewise function by a constant?

For example if i have f(x) = { 10, x != 0, 5, x = 0} and g(x) = 0 Would f(x)g(x) = {0, x!=0 0, x = 0} Thanks. (Sorry for the bad formatting it is the first time I am using this site)
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Properties of piecewise functions and their derivatives: summation and integration

I have the following functions $g(x) = 16x^2(1-x)^2$ on $[0,1]$ $f(x) = 1 - g(x)$ on $[0,0.5]$ and $f(x) = 0$ on $[0.5,1]$ $h(x) = 0$ on $[0,0.5]$ and $h(x) = 1 - g(x)$ on $[0.5,1]$ As one can infer from the definitions, $f(x)$ and $h(x)$ are…
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Problem in Textbook's Piecewise Functions Chapter

Problem: If $f(x)=n$, where $n$ is an integer such that $n\le x\lt n+1$, what is the range of $f(x)$? The answer in the book is the set of all integers. Since this is the answer, isn't $f(x)=n$ enough information to solve this problem? What is the…
54284User
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Piecewise Function

$ f(x)= \begin{cases} 4^x&\text{if}\, x\leq 1\\ \frac{9-x^2}{3-x}&\text{if}\, 1
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Convert piecewise function with ranges to a single mathematical formula

For a programming task (an SQL expression) I need a function made of mathematical operators ($+$, $-$, $*$, $floor$, $ceil$, and comparison operators returning value $0$ (false) or $1$ (true)...) that maps a real value into 4 discrete values…
dolmen
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Continuous from the left/right

Here's a related problem from: Piecewise Function $ f(x)= \begin{cases} 4^x&\text{if}\, x\leq 1\\ \frac{9-x^2}{3-x}&\text{if}\, 1
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How can I create a differentiable function to cap at 100?

How can implement a function similar to $ \ln \bigl( \frac{1}{1+e^{-x}} \bigl) $ It should be below piecewise function and should be differentiable f(n) = \begin{cases} x, & \text{if $x$ < 100} \\ \to 100, & \text{otherwise} \end{cases} I need…
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Confusion in piecewise function notation

I am reading a paper that has the following piecewise function: I am not sure what the arrows and + in the subscript mean here. I am interpreting it as follows, please correct me if this is wrong. It would be great if you kindly direct me to a…
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Piece function with primes and factors

Let $p(x)$ be defined on $2 \le x \le 10$ such that$$p(x) = \begin{cases} x + 1 &\quad \lfloor x \rfloor\text{ is prime} \\ p(y) + (x + 1 - \lfloor x \rfloor) &\quad \text{otherwise} \end{cases}$$where $y$ is the greatest prime factor of $\lfloor…
user771227
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Finding multiple variables to make a function continuous

Given the function: give values for $a$ and $b$ in order that $f(x)$ is continuous at $x=1$ I can't figure out how to calculate $a$. When $x$ is 1 the numerator is 0,. How do I get the limits on either side to be equal?
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Piecewise Simplifcation

I'm just having some trouble understanding a derivation in my notes. How did it go from that first line to the second? \begin{align*} h_n&=\frac{Kj}{2r\sin(\omega_0)}\left(-(re^{j\omega_0})^{n+1}u_{n+1}+(re^{-j\omega_0})^{n+1}u_{n+1}\right)…
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Find the values so the function is differentiable

Struggling with this for some reason. I know that you have to check for continuity but I am confusing myself. Find the values of a and b so that the following function is differentiable in $\mathbb{R}$. $$ f(x) = \begin{cases} -3x+a, & x\ne2…
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Piecewise Functions when continuous implications

Let $h(x)$ be a piecewise function in which $$h(x) = \begin{cases} 1+x &\text{if $x < 0$}\\ ax+b & \text{if $0\le x\le 1$}\\ 4x+2 & \text{if $x > 0$} \end{cases} $$ And also note that $h(x)$ is continuous at $x=0$ and $x=1$. Given these…
sangstar
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Piecewise function is it continuous?

Let ⎧ -x+b, if x < -3 f(x) = ⎨ 2, if x = -3 ⎩ (−2)/(x−b) + 1, if x > -3 (and x≠b) What I tired is to set -x + b = $(−2)\over(x−b)$ + 1 where x is approaching -3. I get b = $7±\sqrt{33}\over{-2}$. Which is…