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makansij
  • Member for 8 years, 11 months
  • Last seen more than a month ago
  • Dockweiler, CA 90007, USA
16 votes
2 answers
24k views

When is a symmetric matrix invertible?

9 votes
2 answers
9k views

Ensuring that a symmetric matrix with nonnegative elements is positive semidefinite

8 votes
7 answers
4k views

Is the intersection of two orthogonal planes a line, or the zero vector?

6 votes
2 answers
2k views

How is $f(x)=x+1$ not backwards stable if I consider the error propagated in the addition?

5 votes
4 answers
3k views

Does least squares (approximate solution) minimize the orthogonal distance of $b$ to $Ax$, or does it minimize the error projected along the $b$ axis?

5 votes
1 answer
1k views

What does it mean for something to be strictly less than $\epsilon$ for an arbitrary $\epsilon$?

4 votes
3 answers
6k views

How do the normal equations *always* have a solution?

4 votes
1 answer
328 views

Is this book implying that elliptic PDE is the only one that can be minimized by calculus of variations?

3 votes
2 answers
6k views

Confusion on terminology: "vector rejection", "vector projection", and "orthogonal projection"?

3 votes
2 answers
2k views

How to find difference between consecutive double precision numbers?

3 votes
1 answer
267 views

How to prove that Leven Marquardt always results in a descent direction (Proof verification)?

3 votes
1 answer
1k views

Why is it a requirement that we follow the central path in the interior point method?

3 votes
2 answers
2k views

How to show $\partial f(x) =\{\nabla f(x) \}$ for a convex differentiable function?

3 votes
3 answers
387 views

How are both of these true: $J = \nabla f ^T $, and also $\nabla f = J^T f$?

2 votes
1 answer
263 views

Is relative boundary of the epigraph the same as relative interior of the domain of a convex function?

2 votes
2 answers
375 views

Learn Noise / Error in Least Squares If We Know Its Form?

2 votes
1 answer
2k views

How to apply SVD to real data to reduce the number of parameters?

2 votes
1 answer
270 views

If $V \in \mathbb{R}^{n \times n}$ is an orthogonal matrix, and $V^T e=0$, ($e$ is the ones vector) then is it true $V_m^T e = 0\, \forall \, m<n$? [closed]

2 votes
1 answer
64 views

Difference between $0<m<f(x)\,, \forall x$ versus $0<f(x)\,, \forall x$?

2 votes
2 answers
210 views

If $g(x)f'(x) = f(x)g'(x)$ show there is some $c$ in $\mathbb{R}$ such that $f(x)=cg(x) \forall x$ in $\mathbb{R}$. (Fitzpatrick 4.3, 15)

2 votes
1 answer
567 views

How to geometrically interpret conditional expectation property tower rule??

2 votes
1 answer
61 views

Applying comparison theorem to limits when inequality is known

2 votes
1 answer
39 views

How to compute number of ways one S and one F can be chosen from group of (2F, 2S, 2J, 2R)?

2 votes
2 answers
210 views

How to produce an $n \times n$ matrix from an $n^2 \times 1$ vector?

2 votes
1 answer
5k views

Why do we need to check both primal and dual feasibility in LP programs?

2 votes
0 answers
803 views

Show when the inequality for matrix-vector multiplication for the 2 norm is an equality?

2 votes
3 answers
1k views

How is the variance equivalent to the following?

2 votes
0 answers
72 views

Chicken or egg problem: Which comes first duality or numerical precision in following the central path in LP?

2 votes
1 answer
313 views

How to prove identity $\nabla f(x) = \nabla F(x)*F(x)$ for 2-norm squared when chain rule says otherwise?

2 votes
2 answers
2k views

How to find the gradient of $f(x)=-\sum_{i=1}^n \log x_i$?

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