In mathematics, a continuous function is a function that does not have any abrupt changes in value, known as discontinuities. More precisely, a function is continuous if arbitrarily small changes in its output can be assured by restricting to sufficiently small changes in its input. If not continuous, a function is said to be discontinuous. Up until the 19th century, mathematicians largely relied on intuitive notions of continuity, during which attempts such as the epsilon–delta definition were made to formalize it.
Continuity of functions is one of the core concepts of topology, which is treated in full generality below. The introductory portion of this article focuses on the special case where the inputs and outputs of functions are real numbers. A stronger form of continuity is uniform continuity. In addition, this article discusses the definition for the more general case of functions between two metric spaces. In order theory, especially in domain theory, one considers a notion of continuity known as Scott continuity. Other forms of continuity do exist but they are not discussed in this article.
As an example, the function H(t) denoting the height of a growing flower at time t would be considered continuous. In contrast, the function M(t) denoting the amount of money in a bank account at time t would be considered discontinuous, since it "jumps" at each point in time when money is deposited or withdrawn.
I recall reading somewhere that the mean value of a continuous variable is situated at a point that acts as a fulcrum about which all other values are considered "weights".
In other words, if we define the mean as
μ = \int^{∞}_{-∞} x ρ(x) dx (where rho is the probability density)
then...
Homework Statement
In the winter, the monthly demand in tonnes, for solid fuel from a coal merchant may be modeled by the continuous random variable X with probability density function given by:
f(x)=\frac{x}{30} 0≤x<6
f(x)=\frac{(12-x)^{2}}{180} 6≤x≤12
f(x)=0 otherwise
(a)...
I was wondering what the majority opinion was on this issue, among physicists and philosophers as well. I can't imagine zooming in a million times smaller than the plank length and still not being at a smallest length, however a discrete universe doesn't make much sense to me.
Are there any...
Hello,
Sorry if the question sounds silly, but can a continuous matrix be seen as a differential operator?
First of all, let me state that I have no idea what a continuous matrix would formally mean, but I would suppose there is such an abstract notion, somewhere?
Secondly, let me tell...
Simple continuous tracking radar system with cantenna
We are in need of a simple radar target tracking signal processing method. It's to be very short range, less than 5 meters. It needs to track a single target that can be moving or stationary at any time. We are using 2.4 GHz ISM band...
Homework Statement
Let f : (-1, 1) → ℝ. f satisfies the intermediate value property and is one-to-one on (-1, 1). Prove f is continuous on (-1, 1)
The Attempt at a Solution
I was thinking that the IVP and one-to-one implies that f should be strictly monotonic and that a strictly monotonic...
Homework Statement
Find the value of p and q that make the function continuous
Homework Equations
f(x)= x-2 if x≥2
\sqrt{p-x^{2}} -2<x<2
q-x if x≤-2
The Attempt at a Solution
lim f(x)= x-2
n→2+
lim f(x)=q-x
n→-2
I really have no idea how to continue,the teacher never explained this and I...
Suppose you have two random samples of the profit margins obtained by two
stock traders, Trader A and Trader B. The first data set consists of 18
data, and the second has 21.
I want to check if there is association between the variables
"type of trader" (values A or B) and "profit margin"...
Homework Statement
If C^1(\mathbb T) denotes the space of continuously differentiable functions on the circle and f \in C^1(\mathbb T) show that
\sum_{n\in\mathbb Z} n^2 |\hat f(n)|^2 < \infty
where \hat f(n) is the Fourier coefficient of f.
The Attempt at a Solution
Since f is...
Suppose that f is continuous function on the interval [a,b]
integral from b to a If(x)I dx =0 if and only if f(x)=0 for all x in [a,b]
ıs it true or false ? ı can prove that if f is zero,integral is zero but ı can,'t do that if integral is zero f is zero
Regards
Hi, can someone give me pointers on this question
Homework Statement
Prove or provide a counterexample: If f : E -> Y is continuous on a
dense subset E of a metric space X, then there is a continuous function
g: X -> Y such that g(z) = f(z) for all z element of E.
The Attempt at a Solution...
Hi, can someone please check if my proof is correct
1. a) Assume f : R -> R is continuous when the usual topology on R is
used in the domain and the discrete topology on R is used in the range. Show
that f must be a constant function.
My attempt :
Let f: R --> R be continuous. Suppose...
Hi,
I am correcting a C code which was written for a flame machine. My desire is to give a burst cool time when the machine working continuously. In deep, user could have the facility to enter the flame time and cool time before a continuous operation. So, i exactly want to off the...
Hi,
I am trying find equations for continuous "stretchy" collisions, in other words, I have two perfectly round objects of known mass, radius, and velocity, and want to collide them and be able to have them squish together and then bounce apart. I am aware of the method of solving for the...
Hello Forum,
there are two typeos of servo motors. One of them is called continuous. does it mean that it can rotate to any angular position, between 0 degrees and 360?
The other type (the non continuous one) still rotates at any angular position, but only within a limited range, like 0 to...
Homework Statement
T or F, If f:ℝ→ℝ is continuous on a dense set of points in ℝ, then f is continuous on ℝ.
Homework Equations
definition of continuity using sequences, maybe?
The Attempt at a Solution
false. Take f(x)= {1 if x\in Q(rational numbers) and 0 if x\in...
Homework Statement
Show that if f: [a,b]→Re is increasing and the range of f is a bounded interval then f is continuous.
Homework Equations
N/A
The Attempt at a Solution
I have no idea where to start, but I decided to start with a couple of things.
Proof: Let f: [a,b]→Re...
Homework Statement
Why is it that continuous functions do not necessarily preserve cauchy sequences.
Homework Equations
Epsilon delta definition of continuity
Sequential Characterisation of continuity
The Attempt at a Solution
I can't see why the proof that uniformly continuous...
Homework Statement
I'm given the pdf and asked to find F(y)/ cdf. I've calculated it many times, but I'm not getting the right numbers. the pdf is
f(y)= .5, ....-2≤y≤0
.75-.25y,...1≤y≤3
0,...elsewhere
so that means
f(y)= 0,...y< -2
0.5, ...-2≤y≤0...
As in my previous thread we had:
"Let f a function which satisfies $$|f(x)|\leq|x| \forall{x\in{\mathbb{R}}}$$
Proof that is continuous at 0.
We concluded that since f(0)=0 then we found a delta equal epsilon so $$|f(x)|≤|x|<ϵ$$.
But now I have:
$$\textrm{g continuous at 0 and...
I don't see the subtle differences between continuous and uniformally continuous functions. What can continuous functinons do that unifiormally continuous functions can't or vice versa?
Homework Statement
Homework Equations
The Attempt at a Solution
I understand that all i need to do is plug these two points into the formula and subtract to get the correct area, but i am not provided a mean or variance as i normally am, so I'm at a loss.
Homework Statement
Suppose that f : ℝ→ℝ is continuous on ℝ and that lim f =0 as x→ -∞ and lim f =0 as x→∞. Prove that f is bounded on ℝ and attains either a maximum or minimum on ℝ. Give an example to show both a maximum and a minimum need not be attained.
The Attempt at a Solution...
Homework Statement
Let f be continuous on the interval [0,1] to ℝ and such that f(0) = f(1). Prove that there exists a point c in [0,1/2] such that f(c) = f(c+1/2). Conclude there are, at any time, antipodal points on the Earth's equator that have the same temperature.
Homework Equations...
Let $f:\mathbb R\to\mathbb R$ be a continuous function of period $2\pi.$ Prove that if $\displaystyle\int_0^{2\pi}f(x)\cos(nx)\,dx=0$ for $n=0,1,\ldots$ and $\displaystyle\int_0^{2\pi}f(x)\sin(nx)\,dx=0$ for $n=1,2,\ldots,$ then $f(x)=0$ for all $x\in\mathbb R.$
I know this has to do with the...
Let X be some topological space. Let A be a subspace of X. I am thinking about the following: If f is a cts function from X to X, and g a cts function from X to A, when is the piece-wise function
h(x) = f(x) if x is not in A, g(x) if x is in A
continuous? My intuition tells me they must agree...
Homework Statement
Let g: ℝ→ℝ satisfy the relation g (x+y) = g(x)g(y) for all x, y in ℝ. if g is continuous at x =0 then g is continuous at every point of ℝ.
Homework Equations
The Attempt at a Solution
Let W be an ε-neighborhood of g(0). Since g is continuous at 0, there is...
When f maps E into a metric space Y: (E is subset of metric space X)
Is it eqivalent to say that f is a continuous mapping and that for a subset E of X, to say that for every p element of E, f is continuous at p.?
thank you
Cardinality of the Preimage f^{-1}(y) of f:X-->Y continuous?
Hi, All:
Let X,Y be topological spaces and f:X-->Y non-constant continuous function.
I'm curious as to whether it is possible for the fiber {f^{-1}(y)} of some y in Y
to be uncountable, given that the fiber is discrete (this...
Homework Statement
Define f:[-1,∞]→ℝ as follows: f(0) = 1/2 and
f(x) =[(1 + x)^(1/2) - 1]/x , if x ≠ 0
Show that f is continuous at 0.
Homework Equations
Definition. f is continuous at xo if xoan element of domain and
lf(x) - f(xo)l < ε whenever lx - xol < δ
The Attempt at...
Can I use the definition of continuity of function from Baby Rudin, setting X as empty set?
Rudin does not specify X is a non-empty set but he supposes p is in X.
Anyway if I use it for empty set X, then is a function with a domain E which is a subset of X continuous at p?
One more...
I'm trying to show that continuous f : [a, b] -> R implies f uniformly continuous.
f continuous if for all e > 0, x in [a, b], there exists d > 0 such that for all y in [a, b], ¦x - y¦ < d implies ¦f(x) - f(y)¦ < e.
f uniformly continuous if for all e > 0, there exists d > 0 such that for...
Homework Statement
Let f_{n}(x)=\frac{-x^2+2x-2x/n+n-1+2/n-1/n^2}{(n ln(n))^2}
Prove f(x) = \sum^{\infty}_{n=1} f_{n}(x) is well defined and continuous on the interval [0,1].
Homework Equations
In a complete normed space, if \sum x_{k}converges absolutely, then it converges.The Attempt at...
or is space itseld quantized meaning an object moving from a to b
would in some way look like A \/\/\/\/\0/\/\/\/ B
or is it smooth and continuous like A--------0------B
?
A function defined on ℝ is continuous at x if given ε, there is a δ such that |f(x)-f(y)|<ε whenever |x-y|<δ. Does this imply that f(x+δ)-f(x)=ε? The definition only deals with open intervals so i am not sure about this. If this is not true could someone please show me a counter example for it...
Homework Statement
assume a function F(x)=(a|x|^(a-1))*(sin(1/x))-((|x|^a)/(x^2))*(cos(1/x)) for x not equal to 0
F(x)=0 for x equal to 0
for what values of a that this function is continuous on R(real number)
Homework Equations
the F(x) is the differentiation of |x|^a sin(1/x)...
function f:R->R can be written as a sum f=f1+f2 where f1 is even and f2 is odd。then if f is continuous then f1 and f2 may be chosen continuous, and if f is differentiable then f1 and f2 can be chosen differentiable
i am quiet confusing this statement , if f1 is continuous f2 is not how their...
Homework Statement
function f:R->R can be written as a sum f=f1+f2 where f1 is even and f2 is odd。show that if f is continuous then f1 and f2 may be chosen continuous, and if f is differentiable then f1 and f2 can be chosen differentiable
2. The attempt at a solution
i have try some...
Homework Statement
Let f : R -> R be a continuous function such that f(0) = 0. If S := {f(x) | x in R} is not
bounded above, prove that [0, infinity) ⊆ S (that is, S contains all non-negative real numbers).
Then find an appropriate value for a in the Intermediate Value theorem...
I need help on alternative motor that I can use for vacuum that can run continuously for 20 hours a day and it should be 12VDC powered.
Basically I am doing a heat exhaust system for a data center. I want to use small pipes so it won't be bulky about 1.5" and for that to work I think strong...
[topology] "The metric topology is the coarsest that makes the metric continuous"
Homework Statement
Let (X,d) be a metric space. Show that the topology on X induced by the metric d is the coarsest topology on X such that d: X \times X \to \mathbb R is continuous (for the product topology on X...
Homework Statement
a) Let {s_{n}} and {t_{n}} be two sequences converging to s and t. Suppose that s_{n} < (1+\frac{1}{n})t_{n}
Show that s \leqt.
b) Let f, g be continuous functions in the interval [a, b]. If f(x)>g(x) for all x\in[a, b], then show that there exists a positive real z>1 such...
Hi All, just a question regarding continuous functions.
From what I understand if x > 2, then any value of 'a' should make this function continuous? Any clarification would be very helpful!
Thanks in advance!
Homework Statement
Let f and g be two continuous functions defined on R.
I'm looking to prove the fact that if they agree on Q, then f and g are identical.
Homework Equations
The Attempt at a Solution
I'm not really sure where to start with this. Can someone point me in the right...
1. Homework Statement
Find the total charge on a circular disc of radius ρ = a if the charge density is given by
ρs = ρs0 (e^−ρ) sin2 φ C/m2 where ρs0 is a constant.
Are the two limits of integration from 0 -> a for ρ and 0->2∏ for φ? In the example given in the notes, ρ varies, instead of...
Homework Statement
Find the total charge on a circular disc of radius ρ = a if the charge density is given by
ρs = ρs0 (e^−ρ) sin2 φ C/m2 where ρs0 is a constant.
Are the two limits of integration from 0 -> a for ρ and 0->2∏ for φ? In the example given in the notes, ρ varies, instead of...
Homework Statement
I am having trouble understanding how
\textit{Δ}\vec{E}\textit{ = k}_{e}\frac{Δq}{{r}^{2}}
(where ΔE is the electric field of the small piece of charge Δq)
turns into
\vec{E}\textit{ = k}_{e}\sum_{i}\frac{{Δq}_{i}}{{{r}_{i}}^{2}}
then into
\vec{E}\textit{ =...
Homework Statement
Homework Equations
The Attempt at a Solution
I can show the second one, i.e. 1/3 [sqrt(y) +1] and need help in showing the first one. Can anyone guide me?