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Feb
1
comment Show that $X_1^T[I_n - X({X^T}X)^{-1}X^T] = 0$
Note that if you can write $X_1 = XC$ for some $C$ you are done.
Feb
1
revised heat equation on a surface
corrected spelling
Feb
1
suggested approved edit on heat equation on a surface
Jan
31
accepted Matrix with maximal rank in a family of matrices
Jan
30
revised Matrix with maximal rank in a family of matrices
fixed grammar
Jan
30
asked Matrix with maximal rank in a family of matrices
Jan
26
comment Determining the convergence of $\sum (-1)^{k-1} \frac{\log k}{\sqrt{k}}$ and a more complicated series
For $ k > 1, \log k > 0,$ and $$k = \exp \log k = 1 + \frac{\log k}{1} + \frac{(\log k)^2}{2!} + \frac{ (\log k)^3}{3!} + \dots +$$, so, $(\log k)^3/6 \leq k$ and $ \log k \leq \sqrt[3]{6k}.$
Jan
25
accepted Invariant subspace of an orthogonal operator.
Jan
24
comment Invariant subspace of an orthogonal operator.
This is neat. Thanks!
Jan
24
revised Invariant subspace of an orthogonal operator.
deleted some unecessary lines.
Jan
24
comment Invariant subspace of an orthogonal operator.
I will update the questions with the original argument, reference, and how I came up with this question from his argument shortly.
Jan
24
comment Invariant subspace of an orthogonal operator.
I have removed all references to argmax.
Jan
24
revised Invariant subspace of an orthogonal operator.
made sure $x_0$ is defined unambiguously
Jan
24
comment Invariant subspace of an orthogonal operator.
It is a $x_0$ with $\|x_0\|=1$ which maximizes $ x^TAx$ over $\{x:\|x\|=1\}.$
Jan
24
asked Invariant subspace of an orthogonal operator.
Jan
23
revised Set of Discontinuities for a function $f$
Changing $ env to $$ environment to make the answer render better. It was not rendering correctly on my laptop.
Jan
23
revised Local maxima or minima of a continuous functions
Fixed spelling
Jan
23
suggested approved edit on Local maxima or minima of a continuous functions
Jan
20
comment Behavior of derivative near the zero of a function.
If $f(x_n)$ is also zero then $f(x)/f'(x)$ may have a removable discontinuity at $x_n$.
Jan
20
comment Behavior of derivative near the zero of a function.
This case must be impossible but I don't see immediately why $f'(x)$ has a zero in every nbd of $0$ which coincides with the zeroes of $f(x)$ and their ratio makes sense.