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md2perpe's user avatar
md2perpe's user avatar
md2perpe
  • Member for 9 years, 9 months
  • Last seen this week
63 votes

Are $\sin$ and $\cos$ the only functions whose derivatives are equal to each other up to a sign?

21 votes
Accepted

Improved intermediate value theorem

19 votes
Accepted

Two Dirac delta functions in an integral?

18 votes

Empty set and empty sum

18 votes
Accepted

What is a pullback of a metric, and how does it work?

16 votes

Reference for Dirac Delta function as gaussian

10 votes

Can a function have a derivative where it has no value?

10 votes
Accepted

Dirac delta solutions

9 votes
Accepted

What number is written?

8 votes
Accepted

Fourier transform of the distribution PV $\left( \frac{1}{x} \right)$

8 votes

Can a number be non-imaginary and non-real?

7 votes

Fourier transform of the principal value distribution

7 votes

Derivative of Heaviside step Function

7 votes

composition of the derivative of Dirac delta with a function

7 votes
Accepted

Reconciling measure theory change of variables with u-substitution

7 votes

Example of an uncountable dense set with measure zero

7 votes

Finding the Derivative of |x| using the Limit Definition

7 votes

2D integration by parts

7 votes

Scaling property of Dirac delta function is not intuitive!

7 votes

Limit $\lim_{\epsilon \rightarrow0} \frac{1}{\sqrt{\epsilon}}\exp\left({-\frac{x^2}{\epsilon}}\right)$ in the sense of distributions

7 votes
Accepted

Derivative and divergence of measures, product of measures and vector field

7 votes
Accepted

If $\phi$ is in $\mathcal S$ and $\phi(0)=0$, is $\int_0^1 \nabla \phi(tx)dt$ in $\mathcal S$ too?

6 votes

If $f$ is a scalar field on $\mathbb{R}^2$, how do I interpret the quantity $x\frac{\partial f}{\partial y} - y\frac{\partial f}{\partial x}$?

6 votes

Wirtinger derivative form of Cauchy–Riemann equations

6 votes

What do the colours on a Mandelbrot Set image represent?

6 votes

Fourier transform for $H(t)$ and test function

6 votes
Accepted

Derivative of the Heaviside step function

6 votes
Accepted

Clean proof of Baker-Campbell-Hausdorff Formula

6 votes
Accepted

$f\in \mathcal{C}^{\infty}_{c}(\mathbb{R})$ such that $f(0)=0$ there exists $g\in\mathcal{C}^{\infty}_{c}(\mathbb{R})$ such that $f(x)=xg(x)$

6 votes

Example of a vector space with different addition/scalar multiplication operators

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