Questions tagged [lambert-w]

Ask Question

For questions related to the Lambert W or product log function, the inverse of $f(z)=ze^z$.

679 questions 1
2 votes 1 answer 83 views +50

Alternative representations for $\int_1^e e^{e^{t W_{-1}\left(\frac{-\ln(t)}{t}\right)}}dt$ and $\int_{e^{-e}}^{e^{\frac1e}}e^{t+W_0(-\ln(t))}dt$?

Some time ago I posted an answer in this post. The original question was about evaluating $$ \lim_{n\to\infty} \int_{0}^{\infty} \frac{e^x}{^{2n}x} \mathrm{d}x $$ where $^{2n}x$ is the power tower of ... user avatar Robert Lee
  • 5,225
2 votes 1 answer 38 views

Lambert W of a constant multiple

$ \ln(cx) $ can be expressed as $ f(c) + \ln(x) $, where $ f(c)=\ln(c) $. Does the lambert W function have a similar property? (Can $ W(cx) $ be expressed as $ f(c)+W(x) $ for some function $ f $). user avatar Sky Jaheim
  • 83
0 votes 0 answers 23 views

Looking for $B$ such that $\Gamma(ax+b) \prod_{i=1}^n (ax+e_i)\sim \Gamma(ax+B)$

Quite often, I need to solve for $x$ $$y=\Gamma(ax+b)\prod_{i=1}^n (c_ix+d_i)\tag 1$$which, numerically does not make much problems looking for the zero of function $$f(x)=\log\Big[\Gamma(ax+b)\Big]+\... user avatar Claude Leibovici
  • 215k
0 votes 1 answer 47 views

Finding zeroes for function $f(t) = e^{k(t-1)} -t$ for $k> 0$ analytically

I tried using Lambert W function the following way $$e^{k(t-1)} -t=0$$ $$e^{k(t-1)}=t$$ $$-ke^{-k} = -kte^{-kt}$$ $$W(-ke^{-k}) = W(-kte^{-kt})$$ $$-k = -kt \implies t = 1$$ but this only gives me one ... user avatar Adam Shegan
  • 11
-1 votes 1 answer 97 views

How to find the solution of $x(e^x)+\ln(x)+c = 0$, where $c$ is constant? [closed]

For $x(e^x)+\ln(x)+c = 0$, where $c$ is constant. I believe the solution is solved using Lambert $W$-function and derivatives, but I can't figured it out, I can't find any ideas can someone tell me ... user avatar gerard hotaro
  • 77
0 votes 1 answer 110 views

Lagrange inversion theorem of $x^r(x+k)$ to generalize the W Lambert function

Motivation: $2$ branches of Lambert $\text W_k(z)$ is a limit of the inverse of $x^n(x+c)$ which is probably expressible in terms of FoxH in Mathematica or through another general hypergeometric ... user avatar Tyma Gaidash
  • 5,332
2 votes 2 answers 64 views

$W_{-1} (x)$ series expansion?

By the Lagrange Inversion Theorem, one can derive the series expansion for the principal branch of $W_0(x)$: $$W_0(x)= \sum_{n=1}^{\infty} \frac{(-n)^{n-1}x^n}{n!}, \, |x| \leq \frac1e$$ For $x \in \... user avatar Mailbox
  • 347
0 votes 0 answers 42 views

Formula for lower branch of Lambert W / Product log function

Is there some direct formula for the W-1 or lower branch of the Lambert W function? I saw that the Python package scipy and the function ... user avatar testerp2034
  • 1
0 votes 0 answers 26 views

Projecting a point onto a convex set given by Log-Sum-Exp

Motivated by a wish to encode signal temporal logic specs (with linear predicates) as optimization problems w/o mixed integer approaches, I've been attempting to find a way to define the projection ... user avatar Zach
  • 56
0 votes 2 answers 88 views

solving for exact solution of $x^{x^x} = 17$

Im trying to solve for the exact solution of $$ x^{x^x} = 17 $$ I understand that the previous solution, $x^x=17$, does not have an exact closed form solution and requires use of the Lambert W ... user avatar Jacob
  • 21
0 votes 1 answer 21 views

Find parameter to catenary interpolate a specific point

I'm working with the catenary equation and this equation is given by $$ f(x) = a \cdot \cosh\left(\dfrac{x}{a}\right) $$ I know this function pass at the point $(x_0, \ y_0)$ and therefore I want to ... user avatar Carlos Adir
  • 175
2 votes 1 answer 52 views

What is the formula for higher integration of Lambert´s W function?

First I will present the notation for higher integration, which I copied from Danya Rose \begin{align} J_x^n(f(x)) = \int ...\int f(x) dx^n \end{align} Here are the higher integrations of the ... user avatar Weeeeeooooo
  • 21
0 votes 0 answers 25 views

An equation involving the incomplete Gamma function

Fix $a, b>0$. For $x >0$, I need to solve the following equation in $y$: $$ \gamma(a, xy) = y^b $$ where $\gamma(s,t) = \int_0^t r^{s-1}e^{-r} dr$ is the incomplete Gamma function. How do I ... user avatar gm01
  • 59
0 votes 1 answer 75 views

How to Interpret Lambert W Function?

I just used an online calculator to calculate the following values of t. 1.) I am confused about how I am supposed to interpret the $W_{-1}$ and $W_0$. Could anyone help me out? Here is my original ... user avatar Benjamin Little
  • 27
0 votes 1 answer 32 views

How is $W_{-1}(-\frac{2}{3}\cdot e^{-\frac{2}{3}}) = -1.429$ if $W(x)$ is inverse of $f(x)=x\cdot e^x;x<-1$?

$$ f(x)=x\cdot e^x \space ;\space x<-1 \\ W_{-1}(x)=f^{-1}(x) \\ W_{-1}(x\cdot e^x)=f^{-1}(x\cdot e^x)=x $$ But $W_{-1}(-\frac{2}{3}\cdot e^{-\frac{2}{3}}) = -1.429$ not $-0.66 \dot 6$? It may be a ... user avatar UWU gg
  • 43

15 30 50 per page1234546

You Might Also Like