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| bio | website | |
|---|---|---|
| location | ||
| age | 28 | |
| visits | member for | 2 years, 9 months |
| seen | 10 hours ago | |
| stats | profile views | 3,195 |
Almost all of the questions on the front page these days are homework questions or textbook exercises. I think I'll be spending a lot less time here.
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Mar 11 |
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Differentiation in 3d of sin root and fractions in one! -> to find the normal to a function If you say so, but there is a big difference between the PDF's $\left(-\frac{\partial f}{\partial x},1,-\frac{\partial f}{\partial z}\right)$ and rlgordonma's $\left(-\frac{\partial f}{\partial z},\frac{\partial f}{\partial x}\right)$... |
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Mar 11 |
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Differentiation in 3d of sin root and fractions in one! -> to find the normal to a function It's probably not a great idea to ask strangers on the internet for help if you have no way to tell whether the answers you get make sense for your question. If I give you an answer that contradicts the existing one, how will you know which one is right? Maybe rlgordonma misinterpreted and gave an answer to a different problem. Maybe I'm the one misinterpreting your question. You need to go back and check some basic properties that the normal vector you want ought to have, so that you can look at the answers and say, "Thanks, that looks right", or, "That doesn't make sense because..." |
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Mar 11 |
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Math hack for solving system of equations Also consider $\begin{bmatrix}-10^{-5}&1\\1&-10^{-5}\end{bmatrix}$... |
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Mar 11 |
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Math hack for solving system of equations This sounds like a really bad idea. Take the matrix $\begin{bmatrix}0&1\\1&0\end{bmatrix}$ and compare the LU decompositions you get with pivoting and with your approach without pivoting. |
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Mar 11 |
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Notation: Concatenate two functions (piecewise) / Concatenate two vectors, lists or tuples @user4514, this is the notation for vector concatenation. In linear algebra, $[\mathbf x\ \mathbf y]$ means nothing but the vector $[x_1\ x_2\ \ldots\ x_m\ y_1\ y_2 \ldots y_n]$, because in linear algebra we do not have nested lists. |
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Mar 11 |
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Graph of a curve Write $z=x+iy$ and expand $\lvert z+z^{-1}\rvert^2=2^2$ to get a quadratic in $x^2$ and $y^2$, then apply the quadratic formula to solve for $x^2$. |
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Mar 11 |
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Is all algebraic commutative operation always associative? Averaging two numbers. |
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Mar 11 |
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Correct way of saying that some value depends on another value x only by a function of x You could say that $f(x)$ is "determined" by $\hat x$. That might not be clear to everyone, so you should spell out that $f(x_1)=f(x_2)$ whenever $\hat x_1=\hat x_2$. For example, if two random variables have the same distribution, then they have the same expectation. |
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Mar 11 |
reviewed | Leave Open Fourier Transform of a function under an arbitrary coordinate transform |
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Mar 11 |
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Graph of a curve i.stack.imgur.com/fOreA.png |
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Mar 11 |
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Mean matching size Hmmm, the tooltip for the downvote button does say "This question does not show any research effort..." |
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Mar 11 |
awarded | Autobiographer |
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Mar 11 |
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A basic question about iteration methods Jori's answer is right. To paraphrase Hurkyl's comment on another thread, there's always an easy way to reduce the number of iterations: each iteration, you do two steps of some other algorithm. :) In the end, what matters is the total compute time it takes to achieve a given accuracy. |
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Mar 11 |
reviewed | Close Linear Transformation Question (Finding Standard Matrix and Image) |
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Mar 11 |
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Ratio of primes $(x^2+x+(5+6m))$ to $(x^2+x+(3+6m))$ The next time you edit the question, please also change the title so it does not consist entirely of math. |
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Mar 11 |
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How to solve this coupled 2nd order Differential equation of a double pendulum- Runge Kutta method Please consider formatting your math using these instructions to make it easier to read. |
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Mar 11 |
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How to solve this coupled 2nd order Differential equation of a double pendulum- Runge Kutta method deleted 2 characters in body; edited tags |
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Mar 11 |
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Points on a plane @Berci: Can you explain why you tagged this graph theory? |
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Mar 11 |
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Graph theory problem (edge-disjoint matchings) You're offering a bounty for someone to do your homework? |
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Mar 11 |
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How does one verify if a vector is really recovered? Can you give some context or examples for the benefit of people not intimately familiar with compressed sensing? |
