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 Yearling
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Feb
9
comment Dimension of the sum of subspaces
@Leon, they are the same thing.
Jan
31
revised Should I trust Mathematica or numerous other sources on this Fourier transform
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Jan
28
comment How/why does matrix multiplication work to do a linear fit?
Yeah guys, I agree with Chris. He has a concrete problem (or rather a solution) he needs to understand. To understand this, he might have to dive deeper on some aspects. It does not help him, nor is it very constructive, to point out that he needs to "learn more about X".
Jan
28
comment How/why does matrix multiplication work to do a linear fit?
It might be easier to explain if you post the pseudocode of what you are doing and what the procedure you found is doing. By the way, what is IDL?
Jan
18
awarded  Yearling
Dec
21
comment If $A\in\Bbb \{\pm1,0\}^{n\times n}$ is symmetric of rank $<n$, does $A-I$ have rank $n$?
I guess it means that all elements should be $1$ or $-1$, but then "-1 or 0 as diagonals" is slightly confusing, since 0 wouldn't be allowed anyway.
Dec
13
answered Is it possible to compute factorials by converting to matrix multiplications?
Dec
13
comment Tensor with multi-rank $(1,1,1)$
Is this an assignment for a course?
Dec
13
comment Proving a matrix has an inverse…
Yes, you should try your approach.
Dec
13
comment Is it possible to compute factorials by converting to matrix multiplications?
Well, the factorial recurrence relation is not linear with constant coefficients. The coefficient changes.
Dec
13
comment How to sum some unknowns to make underdetermined system determined with $A$ being a binary matrix
This question is missing some information. What do you mean by $A'x' = b$ is equivalent to $Ax = b$? What is $term(x_i')$? Your definition of $x'$ is not clear and does not seem to make sense in your example.
Dec
13
revised What does the solution of a PDE represent?
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Dec
13
reviewed Leave Open How can we calculate the degree of angle made by the matches?
Dec
12
reviewed Approve The Number of Standard Young Tableau of a Frame
Dec
12
comment Some basic questions regarding rank-1 matrices
@User001, Thank you for asking a question I enjoyed answering. :)
Dec
12
comment Some basic questions regarding rank-1 matrices
Sorry, I meant $AB$. :)
Dec
12
comment Some basic questions regarding rank-1 matrices
@User001, since $B$ has rank one, there exists an $x$ such that $Bx = y \neq 0$. If $A$ is invertible we know that $Ay \neq 0$, so $AB$ has at least rank one, but we know that $AB$ has at most rank one, so $1 \leq \operatorname{rank}(AB) \leq 1$ so the rank is one. If $A$ would not be invertible, we would not know that $Ay \neq 0$.
Dec
12
comment Some basic questions regarding rank-1 matrices
@User001, yes, it would, I mentioned this under "Definition 1" under the section dealing with $AB$ having rank at most one.
Dec
12
comment Some basic questions regarding rank-1 matrices
"We can deduce that there is also another nonzero eigenvalue since otherwise we'd have rank B = 0." This is not true.
Dec
12
revised Some basic questions regarding rank-1 matrices
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