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I love mountainbike. I hate the Matrix Cookbook.


Jan
15
revised Solving a matrix equation $X=c \cdot AXA' +I$ with a diagonal corrections
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Jan
15
answered Solving a matrix equation $X=c \cdot AXA' +I$ with a diagonal corrections
Jan
14
revised How to calculate the square root of matrix $A+B$ perturbatively?
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Jan
14
revised How to calculate the square root of matrix $A+B$ perturbatively?
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Jan
14
revised How to calculate the square root of matrix $A+B$ perturbatively?
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Jan
14
answered How to calculate the square root of matrix $A+B$ perturbatively?
Jan
13
answered Compute adjugate matrix over commutative ring
Jan
10
comment Distinct determinants of circulants
$a(1)=1,a(2)=2,a(3)=3,a(4)=3,a(5)=5,a(6)=6,a(7)=9,a(8)=11,a(9)=15,a(10)=19.$ The values are exact until at least $n=12$. Thus this sequence is not in oeis.org/A215723
Jan
10
comment Distinct determinants of circulants
@ Turbo , let $a(n)$ be the number associated to $n$. $a(11)=23,a(12)=59,a(13)=56,a(14)=111,a(15)=223,a(16)=258,a(17)=361,a(18)=880,a(‌​19)=1161,a(20)=2327$. Since I use a random research, the true value of $a(n)$ is $\alpha$ (the value which is given above) or $\alpha +1$ or $\alpha +2$.
Jan
10
comment Distinct determinants of circulants
@ Turbo , according to numerical experiments (until $n=17$) the number of distinct absolute values seems to be at least $O(n^2)$.
Dec
5
answered Calculating the dimension of the algebra generated by some given matrices
Dec
1
revised Rank 1 Approximation of Elementwise Inverse Matrix
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Dec
1
answered Rank 1 Approximation of Elementwise Inverse Matrix
Nov
28
comment Resolvent of a triangular matrix
In my mind "no kidding"="is it a joke ?", that is about the Michele's sentence: " where $p_A$ is the characteristic polynomial of $A$, which is easy to compute once we know an eigendecomposition of A"; that is funny when one knows that $A$ is a triangular matrix. This seems to me absolutely innocuous. Compare with "Récoltes et semailles", the book written by Grothendieck; at least, read the introduction (chapter 0).
Nov
28
revised Resolvent of a triangular matrix
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Nov
27
revised Resolvent of a triangular matrix
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Nov
26
answered Resolvent of a triangular matrix
Nov
26
comment Unitary factor in polar decompositions
@ Lin , I don't think so ; yet even if $-1$ is never an eigenvalue, that does not imply that $C_n<2$ because $C_n$ may be a LimitSup.
Nov
26
answered Characterizing space that preserves positive-definiteness property
Nov
25
revised Unitary factor in polar decompositions
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