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Jun
18
answered Quartic Solution on Wikipedia special cases problem $S=0$ how to “change the choice of cubic root”?
Jun
18
answered Quartic Solution on Wikipedia special cases problem $S=0$ how to “change the choice of cubic root”?
Jun
15
answered A misleading commutative diagram
Jun
15
comment A misleading commutative diagram
By the definition of commutative diagram, wouldn't you need at least a triangle to imply that $\phi$ is a self-inverse? I don't see how the bottom diagram implies this.
Jun
15
comment Why ∫ dn is = N?
You should be careful about $n$ vs. $N$. In mathematics the two are always considered to be two separate variables. Your mixing of the two just makes things more confusing.
Jun
15
comment Computer algebra system for solving systems of partial differential equations / PDEs
Numerical PDE solvers are a dime a dozen, and the one you should use depends very much on the PDE. Symbolic solvers are much rarer. You should clarify what kind of PDEs you have and what kind of solutions you are looking for.
Jun
14
answered Computer algebra system for solving systems of partial differential equations / PDEs
May
19
comment Is $\frac{\textrm{d}y}{\textrm{d}x}$ not a ratio?
@JohnRobertson of course it is. That's the whole point here, that this sort of "fake proof" thinking leads to wrong results here. I blatantly ignore the fact that $d \neq \partial$ (essentially), and I also completely ignore what $F$ really is. My only point here is that if you try to use this as a mnemonic (or worse, a "proof" method), you will get completely wrong results.
Feb
19
comment Why is the inverse of a sum of matrices not the sum of their inverses?
In general, any identity that is not true for real numbers is not going to be true for matrices.
Feb
9
comment Algorithms for Symbolic Manipulation
I don't think the WolframAlpha step-by-step integration is using the Risch algorithm. It's likely just using a rules based system with pattern matching.
Feb
5
comment An impossible sequence of Tetris pieces.
Wait, so is it or isn't it true that the line piece is drawn with decreased probability?
Jan
8
comment Finding the location of an image of the Mandelbrot set
Note that the linked image (which I guess you edited out of my question) is higher quality, because SO compresses the image when you insert it, but the original is uncompressed png.
Jan
8
comment Finding the location of an image of the Mandelbrot set
I was hoping for a general algorithm (or a hint at a computational algorithm), but seeing what @MarkMcClure was able to do for just this one was pretty cool.
Jan
6
comment Finding the location of an image of the Mandelbrot set
I tried uploading the image here, but it looks like SE compresses images, which isn't very helpful. Here is the full uncompressed version.
Jan
6
asked Finding the location of an image of the Mandelbrot set
Dec
16
answered Is Cantor's diagonal argument dependent on the base used?
Dec
12
awarded  Favorite Question
Dec
8
awarded  Caucus
Dec
1
comment Proving formula for sum of squares with binomial coefficient
Note that many (all?) of the proofs here implicitly assume that $n \geq 3$. But you can prove $n = 0, 1, 2$ manually.
Dec
1
answered Proving formula for sum of squares with binomial coefficient