User pitchounet - Mathematics Stack Exchange

22 votes

Dividing by 2 numbers at once, what is the answer?

answered Oct 21, 2014 at 9:18

17 votes

Euclidean distance and dot product

answered Apr 15, 2015 at 21:15

16 votes

How to solve this limits question

answered Sep 9, 2014 at 13:52

15 votes

Accepted

Prove that the integral operator has no eigenvalues

answered Jul 30, 2013 at 15:05

14 votes

Accepted

How are $C^0,C^1$ norms defined

answered Aug 8, 2013 at 16:15

11 votes

The determinant of adjugate matrix

answered Jul 29, 2014 at 15:50

9 votes

Accepted

Sum over fourth power of the sine

answered Apr 28, 2016 at 9:59

9 votes

For which $P \in \mathbb{R}[X]$ is $\sin \circ P$ a periodic function?

answered Sep 21, 2017 at 14:36

8 votes

Evaluate the given limit: $\lim_{x\to \infty} (\sqrt {x-a} - \sqrt {bx})$

answered Jul 18, 2017 at 8:41

7 votes

Evaluating a limit of $f(x)$ given $\lim f(x)/x^2$

answered Sep 16, 2014 at 7:45

7 votes

Accepted

Value of $x^2 \sin (\frac1x)$ at $x=0$

answered Oct 9, 2014 at 17:59

6 votes

Is every basis of a finite-dimensional vector space orthonormal with respect to some inner product?

answered Aug 28, 2014 at 12:12

6 votes

Accepted

Trigonometric Identities for $\sin nx$ and $\cos nx $

answered Aug 26, 2013 at 8:18

6 votes

Accepted

Proof involving Images and Kernels

answered Jul 31, 2013 at 15:32

5 votes

Accepted

proving $\sum_{n=1}^{\infty }\frac{n-2}{3n^3+2n^2}$ converges

answered Jul 11, 2014 at 14:14

5 votes

Accepted

Estimation of the population variance

answered Apr 21, 2015 at 14:43

4 votes

Accepted

Radius of convergence of the series $ \sum\limits_{n=1}^\infty (-1)^n\frac{1\cdot3\cdot5\cdots(2n-1)}{3\cdot6\cdot9\cdots(3n)}x^n$

answered Apr 16, 2015 at 9:01

4 votes

Accepted

Gradient of $\mbox{tr} \left( (AX)^t (AX) \right)$

answered Jan 20, 2015 at 17:14

4 votes

Accepted

About matrix derivative

answered Jul 11, 2014 at 13:42

4 votes

Accepted

Convergence of $\frac{\ln(n)}{n^2}$

answered Oct 23, 2014 at 15:51

4 votes

Accepted

Calculating $\text{D}g$ of $g(x,y) = \int_\frac1x^1\frac1t\exp(t^3x^2y)\text{d}t$

answered Sep 1, 2014 at 14:24

4 votes

Dual basis for $\{1,x,x^2,x^3\}$

answered Jul 31, 2013 at 15:53

4 votes

Integral of $\frac{2x}{\sqrt{1+x^2}}$

answered Jul 23, 2013 at 15:27

4 votes

Accepted

Prove that $\frac{d}{dx}\int_0^xf(x,y)dy = f(x,x)+\int_0^x\frac{\partial}{\partial x}f(x,y)dy$

answered Oct 5, 2013 at 16:41

4 votes

Accepted

Composition of exponential with an isometry

answered Jul 19, 2017 at 11:11

3 votes

Integrating $\int_{0}^{+\infty} e^{-st} \cos(at)\,dt$ using the complex exponential

answered Sep 12, 2017 at 17:56

3 votes

convergence of $\int_0^{\infty}\frac{2x}{e^x-e^{-x}}dx $

answered Jul 18, 2017 at 15:02

3 votes

Converting riemann sum to definite integral

answered Sep 28, 2017 at 20:32

3 votes

Accepted

Do you have any idea on this scalar-by-matrix derivative?

answered Sep 29, 2017 at 8:42

3 votes

Accepted

What is the derivative of the function $f(x)=ix?$ Is it $i$?

answered Jun 15, 2020 at 16:57

Stack Exchange Network

188 Answers

Dividing by 2 numbers at once, what is the answer?

Euclidean distance and dot product

How to solve this limits question

Prove that the integral operator has no eigenvalues

How are $C^0,C^1$ norms defined

The determinant of adjugate matrix

Sum over fourth power of the sine

For which $P \in \mathbb{R}[X]$ is $\sin \circ P$ a periodic function?

Evaluate the given limit: $\lim_{x\to \infty} (\sqrt {x-a} - \sqrt {bx})$

Evaluating a limit of $f(x)$ given $\lim f(x)/x^2$

Value of $x^2 \sin (\frac1x)$ at $x=0$

Is every basis of a finite-dimensional vector space orthonormal with respect to some inner product?

Trigonometric Identities for $\sin nx$ and $\cos nx $

Proof involving Images and Kernels

proving $\sum_{n=1}^{\infty }\frac{n-2}{3n^3+2n^2}$ converges

Estimation of the population variance

Radius of convergence of the series $ \sum\limits_{n=1}^\infty (-1)^n\frac{1\cdot3\cdot5\cdots(2n-1)}{3\cdot6\cdot9\cdots(3n)}x^n$

Gradient of $\mbox{tr} \left( (AX)^t (AX) \right)$

About matrix derivative

Convergence of $\frac{\ln(n)}{n^2}$

Calculating $\text{D}g$ of $g(x,y) = \int_\frac1x^1\frac1t\exp(t^3x^2y)\text{d}t$

Dual basis for $\{1,x,x^2,x^3\}$

Integral of $\frac{2x}{\sqrt{1+x^2}}$

Prove that $\frac{d}{dx}\int_0^xf(x,y)dy = f(x,x)+\int_0^x\frac{\partial}{\partial x}f(x,y)dy$

Composition of exponential with an isometry

Integrating $\int_{0}^{+\infty} e^{-st} \cos(at)\,dt$ using the complex exponential

convergence of $\int_0^{\infty}\frac{2x}{e^x-e^{-x}}dx $

Converting riemann sum to definite integral

Do you have any idea on this scalar-by-matrix derivative?

What is the derivative of the function $f(x)=ix?$ Is it $i$?