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Dec
8
revised PDF of e raised to an exponential random variable
Added math markup
Dec
8
comment How to solve z^6 = -15625?
Substitute $y = z^2$ in the second equation and solve for $y$.
Dec
8
suggested suggested edit on PDF of e raised to an exponential random variable
Dec
6
comment simple tools to extract Re,Im,Abs… of any complex function
No, they don't. The coefficients Antonio was talking about are a property of the function, not the parameter (the Maclaurin coefficients are the Taylor coefficients at zero, i.e. $a_n = \frac{\partial^n f(0)}{n!}$). This is quite a special set of functions, essentially all real analytic functions extended to the complex plane.
Dec
5
revised How to find the minimum of the function?
Fixed math markup
Dec
5
suggested suggested edit on How to find the minimum of the function?
Dec
5
comment simple tools to extract Re,Im,Abs… of any complex function
You are not only using $\arg(f(z)) = \theta \Leftrightarrow \arg(f(z^*)) = -\theta$ but also $|f(z)| = |f(z^*)|$ which is together (if I'm not mistaken) equivalent to $f(z)^* = f(z^*)$.
Dec
5
comment simple tools to extract Re,Im,Abs… of any complex function
@Eddy, what do you mean by "complex transformation"? What do you mean by "preserve angles"? The first set of equations is very well known and used all the time while the second set relies on a property ($f(z)^* = f(z^*)$) that you neither define nor show for the function you apply it to.
Dec
5
comment simple tools to extract Re,Im,Abs… of any complex function
What exactly are you asking? The formulas for real part and imaginary part are pretty standard, your formulas for sine and cosine follow directly from Euler's formula. The formula using the logarithm is one particular definition of the logarithm. The formulas for the functions you gave below are not quite correct, since you omit the $z$ dependence of $\theta$ and $f(z)^* \ne f(z^*)$ in general.
Dec
5
suggested suggested edit on $\int_0^\pi\int_0^\infty e^{-xy}\sin kx~dy~dx=$ ?
Nov
11
revised Algebra Math Contest Question
Fixed math markup
Nov
11
comment Algebra Math Contest Question
The dollar sign \$ is the magic character to enter math mode ;)
Nov
11
suggested suggested edit on Algebra Math Contest Question
Oct
28
comment Square of 2-norm
Assuming $Y$ and $Z_i$ are simply vectors in $\mathbb{R}^n$, your equation reads $\sum_{k=1}^n (Y_k - (Z_i)_k/x)^2 = 2t$, which is simply a quadratic equation.
Oct
28
comment Rational + irrational = always irrational?
$x+1 = \frac{a}b + 1 = \frac{a}b + \frac{b}b = \frac{a + b}{b}$
Sep
30
comment Surprising identities / equations
Note that $\sinh(x) = \frac 12 (\mathrm e^x - \mathrm e^{-x})$, so in fact you have "only" a combination of exponential functions under the integral. And it would be more impressive if the RHS was missing the $\pi$.
Sep
30
revised Surprising identities / equations
added 88 characters in body
Sep
30
revised Surprising identities / equations
added 18 characters in body
Sep
26
revised Simplest or nicest proof that $1+x \le e^x$
Fixed math markup
Sep
26
revised Surprising identities / equations
added 14 characters in body