Composition of two differentiable functions

In summary, the conversation discusses the differentiability of the composition of two functions and the use of the chain rule to find the derivative. The speaker also mentions a common pet peeve about using the notation h(k(x)) to represent a function, and explains the correct notation to use.
  • #1
michonamona
122
0

Homework Statement


Is the composition of two differentiable functions always differentiable?

E.x.

h(x) = sin(x)
k(x) = 1/x for x not equal 0

Does this automatically mean h(k(x)) is differentiable?

Thank you,

M
 
Physics news on Phys.org
  • #2
Sure. You even know a formula for the derivative, right?
 
  • #3
I'll just comment about one of my little pet peeves. h(k(x)) is a number, not a function. The function you have in mind is written as [itex]h\circ k[/itex] or [itex]x\mapsto h(k(x))[/itex]. (Note the special "mapsto" arrow).
 
  • #4
Thank you for your replies.

Sure. You even know a formula for the derivative, right?

So the composition of two differentiable functions is ALWAYS differentiable? I know the derivative of their composition, we just use the chain rule.

I'll just comment about one of my little pet peeves. h(k(x)) is a number, not a function. The function you have in mind is written as LaTeX Code: h\\circ k or LaTeX Code: x\\mapsto h(k(x)) . (Note the special "mapsto" arrow).

Thanks Fredrik. I never thought about that. Now I understand why they always use LaTeX Code: h\\circ k when referring to composition of functions.
 

1. What is the definition of the composition of two differentiable functions?

The composition of two differentiable functions, denoted as (f ∘ g)(x), is a new function that results from applying one function (g) to the output of another function (f). In other words, the output of f becomes the input of g.

2. How is the composition of two differentiable functions calculated?

The composition of two differentiable functions can be calculated using the chain rule, which states that the derivative of the composition of two functions is equal to the product of the derivatives of each individual function.

3. What is the significance of differentiability in the composition of two functions?

When two functions are differentiable, it means that they have a well-defined derivative at every point in their domain. This allows us to calculate the derivative of the composition of two functions using the chain rule.

4. Can the composition of two differentiable functions be non-differentiable?

Yes, it is possible for the composition of two differentiable functions to be non-differentiable. This can occur when the two functions have a discontinuity or a point where the derivative is undefined in their composition.

5. How is the composition of two differentiable functions used in real-world applications?

The composition of two differentiable functions is commonly used in physics, engineering, and economics to model real-world phenomena. For example, in physics, the composition of position and velocity functions can be used to calculate the acceleration of an object at a given point in time.

Similar threads

  • Calculus and Beyond Homework Help
Replies
3
Views
893
  • Calculus and Beyond Homework Help
Replies
7
Views
250
  • Calculus and Beyond Homework Help
Replies
26
Views
883
  • Calculus and Beyond Homework Help
Replies
0
Views
136
  • Calculus and Beyond Homework Help
Replies
5
Views
523
  • Calculus and Beyond Homework Help
Replies
1
Views
253
  • Calculus and Beyond Homework Help
Replies
6
Views
1K
  • Calculus and Beyond Homework Help
Replies
7
Views
2K
  • Calculus and Beyond Homework Help
Replies
8
Views
206
  • Calculus and Beyond Homework Help
Replies
1
Views
691
Back
Top