1,531 reputation
825
bio website about:blank
location Berlin, Germany
age 19
visits member for 3 years, 7 months
seen Jul 16 at 0:07

I'm a highschool student from Germany interested in functional programming, especially Haskell.


Sep
13
comment Database for mathematical syntax
@3Sphere Such a reference is quite useful if you see a formula in the Internet or in a paper where the author sees no reason to include a syntax definition. So even a lookup with many definitions is great, as one can often tell the right one from the context.
Sep
5
comment Solving $8=x(2(1-\sqrt{5}))+(1-x)(2(1+\sqrt{5}))$
There is a simple way: Just use Wolfram Alpha
Aug
29
comment Reducing the time to calculate Collatz sequences
@Thijs Good point. Thank you!
Aug
29
comment Reducing the time to calculate Collatz sequences
@Qiachu But then, I would need to save all that information. Assume, that I want to test all $n$ in the intervall $[1,1\,000\,000\,000]$ - I would need about 1 GiB just for caching! But otherwise, a good idea.
Aug
8
comment How many real roots are there to $2^x=x^2$?
@Arturo Err, that would make it clearer, but the time for editing is up.
Aug
8
comment How many real roots are there to $2^x=x^2$?
@Arturo This was meant because the answerer stated, that $x = 2, x = 4$ are the only solutions.
Aug
8
comment How many real roots are there to $2^x=x^2$?
Why is $x\approx-0.76666469596212309311$ a solution?
Jul
7
comment Mathematical Career Advice to a young 16 year wannabe mathematician
@sigma.z.1980 It's good to know, that other people have the same opinion as me.
Jun
15
comment All functions $\frac{1}{f\left(y^2f(x)\right)} = \big(f(x)\big)^2\left(\frac{1}{f\left(x^2-y^2\right)} + \frac{2x^2}{f(y)}\right)$
@J. J. Ah, thanks. I didn't read the ${}^+$ in $\mathbb R^+$.
Jun
15
comment All functions $\frac{1}{f\left(y^2f(x)\right)} = \big(f(x)\big)^2\left(\frac{1}{f\left(x^2-y^2\right)} + \frac{2x^2}{f(y)}\right)$
I just spotted a possible mistake: $1/f(0)=f(0)$ does not implies $f(0)=1$. It only implies, that $f(0)\in\{-1,1\}$.
Jun
14
comment Is such a cryptographic system possible?
That's a great article!
Jun
14
comment How to solve this recurrence using generating functions?
@muffel IIRC it's written by Graham, Patashnik and Knuth.
Jun
13
comment How to solve this recurrence using generating functions?
@muffel Concrete Mathematics is an awesom book when it comes to sums and generating functions. Just if you're curios.
Jun
13
comment How to solve this recurrence using generating functions?
@muffel For b) and c) recall that $\sum_{i=0}^ni^2=n(n+1)(2n+1)/6$.
Jun
13
comment Expected value for a random variable
Oh, yes. You're right.
May
28
comment Convert any number to positive. How?
In textbooks, the first one is often written $\lvert x\rvert$.
May
24
comment A question on logic - where intuition can fail
@amWhy: Thanks for finding such a good title.
May
24
comment Modulo operation notation
I would write it exactly like you, but add brackets. So $p(x) = (d(x) + b(x)\bmod w(x))$ but $p(x)\not=d(x)+b(x)\mod w(x)$. Notice also, that the spacing is also different.
May
24
comment How to understand and appreciate the prime number industry?
@Sebastien: I would not trust a prime I bought. It could be, that the vendor also sold it to someone else.
May
22
comment Partial sum of ${A \choose i} {B\choose n-i}$, when $B=-1$?
The formula holds for all integer $i$. (According to Knuth in Concrete Mathematics)