User Nathaniel Johnston

32 votes

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Necessary conditions for the existence of solution of Sylvester equation AX=XB

answered Feb 29, 2020 at 21:24

31 votes

Square root of doubly positive symmetric matrices

answered Oct 18, 2020 at 10:41

31 votes

What is the intuition for the trace norm (nuclear norm)?

answered Aug 6, 2017 at 0:49

28 votes

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Are infinite planar graphs still 4-colorable?

answered Dec 15, 2013 at 2:25

22 votes

Which theorems have Pythagoras' Theorem as a special case?

answered May 5, 2022 at 12:08

19 votes

When is 2 qualitatively different from 3?

answered Nov 9 at 18:57

18 votes

Accepted

positive not completely positive maps

answered Jul 15, 2015 at 16:57

17 votes

Operator norm of square root of matrix vs original

answered Dec 6, 2019 at 0:42

17 votes

Possible values of the determinant for matrices with elements $\{1, 0, -1\}$

answered Apr 17, 2022 at 22:45

16 votes

Find the determinant of a matrix given the determinant of all $p\times p$ sub-matrices?

answered Feb 21, 2022 at 17:09

15 votes

Is there such a thing

answered Dec 22, 2013 at 23:59

14 votes

How hard (P, NP, NP-hard) is it to compute Schur norms of matrices (as multipliers)?

answered May 19, 2014 at 23:38

12 votes

Conditions for including cones

answered May 1, 2023 at 17:34

12 votes

Invertibility of a matrix defined using inner product

answered yesterday

11 votes

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Equivalence of entrywise 1-norm and Schatten-1 norm

answered Apr 3, 2015 at 1:50

11 votes

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Decomposability of positive maps

answered Jan 10, 2014 at 16:39

11 votes

Linear algebra underlying quantum entanglement?

answered Mar 5, 2020 at 14:00

10 votes

How to check whether a matrix is completely positive or not?

answered Apr 9, 2014 at 23:34

10 votes

Product of the entries of a matrix

answered Jun 1, 2022 at 16:17

9 votes

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Is there a name for this type of matrix?

answered May 24, 2021 at 17:37

9 votes

When is a linear isomorphism of $M_n(\mathbb{C})$ given by unitary conjugation?

answered Jun 25 at 1:40

9 votes

Moments of the trace of orthogonal matrices

answered Nov 6, 2014 at 18:16

9 votes

NP-hard problems in linear algebra and real analysis

answered Apr 2, 2014 at 12:18

8 votes

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elementwise functions of positive definite matrix

answered Jul 22, 2014 at 15:28

8 votes

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Positive-semidefiniteness of a Gram-like matrix

answered Feb 29, 2020 at 14:19

7 votes

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Tensor product of positive linear maps is positive

answered May 14, 2021 at 15:34

7 votes

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Solution to a Sylvester equation with positive definite coefficients

answered Aug 11, 2022 at 20:52

7 votes

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Powers of traces, integrals over spheres and class functions

answered Nov 24, 2014 at 19:26

6 votes

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Non-orthogonal vectors cosine-enhancing transformation

answered Dec 23, 2013 at 2:46

6 votes

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Is the solution of this optimization problem always positive semidefinite?

answered Jun 13, 2017 at 12:58

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62 Answers

Necessary conditions for the existence of solution of Sylvester equation AX=XB

Square root of doubly positive symmetric matrices

What is the intuition for the trace norm (nuclear norm)?

Are infinite planar graphs still 4-colorable?

Which theorems have Pythagoras' Theorem as a special case?

When is 2 qualitatively different from 3?

positive not completely positive maps

Operator norm of square root of matrix vs original

Possible values of the determinant for matrices with elements $\{1, 0, -1\}$

Find the determinant of a matrix given the determinant of all $p\times p$ sub-matrices?

Is there such a thing

How hard (P, NP, NP-hard) is it to compute Schur norms of matrices (as multipliers)?

Conditions for including cones

Invertibility of a matrix defined using inner product

Equivalence of entrywise 1-norm and Schatten-1 norm

Decomposability of positive maps

Linear algebra underlying quantum entanglement?

How to check whether a matrix is completely positive or not?

Product of the entries of a matrix

Is there a name for this type of matrix?

When is a linear isomorphism of $M_n(\mathbb{C})$ given by unitary conjugation?

Moments of the trace of orthogonal matrices

NP-hard problems in linear algebra and real analysis

elementwise functions of positive definite matrix

Positive-semidefiniteness of a Gram-like matrix

Tensor product of positive linear maps is positive

Solution to a Sylvester equation with positive definite coefficients

Powers of traces, integrals over spheres and class functions

Non-orthogonal vectors cosine-enhancing transformation

Is the solution of this optimization problem always positive semidefinite?