User user541686 - Mathematics Stack Exchange

209 votes

8 answers

119k views

Intuitively, what is the difference between Eigendecomposition and Singular Value Decomposition?

asked Mar 4, 2013 at 6:36

145 votes

11 answers

162k views

Physical meaning of the null space of a matrix

asked Feb 9, 2011 at 7:16

118 votes

4 answers

12k views

What are the Axiom of Choice and Axiom of Determinacy?

asked Jul 20, 2011 at 7:20

44 votes

3 answers

43k views

Non-power-of-2 FFT's?

asked Oct 30, 2011 at 7:08

41 votes

8 answers

96k views

Fourier transform of unit step?

asked Oct 19, 2011 at 6:01

30 votes

3 answers

13k views

Is a Fourier transform a change of basis, or is it a linear transformation?

asked Mar 23, 2012 at 9:13

28 votes

5 answers

13k views

Largest integer that can't be represented as a non-negative linear combination of $m, n = mn - m - n$? Why?

asked Sep 23, 2011 at 14:31

18 votes

3 answers

8k views

Why the Fourier and Laplace transforms of the Heaviside (unit) step function do not match?

asked Apr 10, 2012 at 1:58

15 votes

2 answers

3k views

Is this matrix diagonalizable? Wolfram Alpha seems to contradict itself...

asked Oct 30, 2012 at 2:50

12 votes

4 answers

2k views

Is there such a thing as "quadratic independence" (and higher generalizations of linear independence)?

asked Apr 28, 2014 at 8:18

12 votes

5 answers

4k views

Does the phrase "instantaneous frequency" make sense?

asked Nov 24, 2011 at 22:47

8 votes

2 answers

525 views

Must every event have a probability?

asked Nov 10, 2011 at 10:50

8 votes

1 answer

15k views

Is there a meaningful distinction between "direct" and "iterative" methods for solving equations?

asked Apr 23, 2015 at 16:05

7 votes

3 answers

2k views

Universal quadratic formula?

asked May 5, 2015 at 7:22

7 votes

2 answers

2k views

How to take partial derivatives of functions whose inputs depend on the same variable?

asked Jan 30, 2014 at 3:46

6 votes

2 answers

22k views

Matrix with orthogonal columns? [duplicate]

asked May 8, 2013 at 23:19

6 votes

2 answers

267 views

NP-hard optimization problems for which approximations would be useless?

asked Feb 24, 2015 at 0:46

5 votes

2 answers

11k views

Newton's method vs. gradient descent with exact line search

asked Feb 17, 2015 at 21:53

5 votes

3 answers

174 views

Is there a faster way to compute $\left\lfloor{(k + 1)m \over n}\right\rfloor - \left\lfloor {km\over n}\right\rfloor$?

asked Apr 4, 2021 at 12:28

5 votes

1 answer

85 views

Can (x(t), y(t)) generate a surface? If so, can the surface be continuous?

asked Nov 13, 2012 at 21:41

5 votes

1 answer

9k views

How to find a vector potential (inverse curl)?

asked Apr 7, 2012 at 21:06

5 votes

3 answers

1k views

Find all invertible $n\times n$ matrices $A$ such that $A^2 + A = 0$

asked Feb 28, 2011 at 3:12

5 votes

5 answers

2k views

Transformation T is... "onto"?

asked Jan 31, 2011 at 9:32

4 votes

3 answers

1k views

How to calculate the probability of an event when you don't know the initial probabilities?

asked Mar 31, 2012 at 22:42

4 votes

1 answer

2k views

"Symmetric" numerical computation of second derivative

asked Mar 10, 2015 at 16:15

4 votes

4 answers

519 views

Why does gradient descent make sense?

asked Oct 21, 2014 at 20:29

4 votes

2 answers

388 views

Proving the shortest function connecting two points is a straight line WITHOUT assuming the Euler-Lagrange equation

asked Dec 9, 2014 at 12:16

3 votes

2 answers

5k views

Gradient descent vs. Newton's method -- which one requires more computation?

asked Aug 12, 2014 at 10:15

3 votes

0 answers

88 views

Any reason not to define a derivative as the average of the derivatives on all sides?

asked Jun 18, 2016 at 21:21

3 votes

1 answer

82 views

Why is the solution to $y' = y^n$ always in polynomial form EXCEPT when $n = 1$?

asked Jun 4, 2015 at 9:44

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69 Questions

Intuitively, what is the difference between Eigendecomposition and Singular Value Decomposition?

Physical meaning of the null space of a matrix

What are the Axiom of Choice and Axiom of Determinacy?

Non-power-of-2 FFT's?

Fourier transform of unit step?

Is a Fourier transform a change of basis, or is it a linear transformation?

Largest integer that can't be represented as a non-negative linear combination of $m, n = mn - m - n$? Why?

Why the Fourier and Laplace transforms of the Heaviside (unit) step function do not match?

Is this matrix diagonalizable? Wolfram Alpha seems to contradict itself...

Is there such a thing as "quadratic independence" (and higher generalizations of linear independence)?

Does the phrase "instantaneous frequency" make sense?

Must every event have a probability?

Is there a meaningful distinction between "direct" and "iterative" methods for solving equations?

Universal quadratic formula?

How to take partial derivatives of functions whose inputs depend on the same variable?

Matrix with orthogonal columns? [duplicate]

NP-hard optimization problems for which approximations would be useless?

Newton's method vs. gradient descent with exact line search

Is there a faster way to compute $\left\lfloor{(k + 1)m \over n}\right\rfloor - \left\lfloor {km\over n}\right\rfloor$?

Can (x(t), y(t)) generate a surface? If so, can the surface be continuous?

How to find a vector potential (inverse curl)?

Find all invertible $n\times n$ matrices $A$ such that $A^2 + A = 0$

Transformation T is... "onto"?

How to calculate the probability of an event when you don't know the initial probabilities?

"Symmetric" numerical computation of second derivative

Why does gradient descent make sense?

Proving the shortest function connecting two points is a straight line WITHOUT assuming the Euler-Lagrange equation

Gradient descent vs. Newton's method -- which one requires more computation?

Any reason not to define a derivative as the average of the derivatives on all sides?

Why is the solution to $y' = y^n$ always in polynomial form EXCEPT when $n = 1$?