WolframAlpha wrong(?) graph

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I had a question to plot a graph of

$\space \space\LARGE y=x^{x^{x^{x^{...}}}}$

Which (according to me) is equivalent to

$\large y=x^y \Rightarrow y^{\frac{1}{y}}=x$


So i plotted them in my copy (by taking dozens of different values of y to get x)

To check my graph i plotted them in both "DESMOS" and "WOLFRAMALPHA"


The Results:

Desmos: (Same as mine!) desmos

WolframAlpha: WA

Why does the graph in the case of WolframAlpha going towards $-x$-axis?

3

There are 3 best solutions below

9
On BEST ANSWER

The Wolfram Alpha one doesn't seem to start at $ x=0 $ (look at the numbers at the bottom).

4
On

This is not an answer but it is too long for a comment.

If you are concerned by the plot of $y$ as a function of $x$ such that $\space y^{1/y}=x$, it means that $$y=-\dfrac{W(-\log (x))}{\log (x)}$$ where appears Lambert function.

In the real domain, $x$ must be positive and function $W(a)$ is only defines if $a \geq -\frac 1e$ which makes $0 < x \leq e^{\frac{1}{e}}\approx 1.44467$ and $y$ varies between $0$ and $e$. At both ends, the tangent to the curves is vertical.

May I suggest you ask Wolfram Alpha to plot the equation I wrote and I suppose that you will get something similar to what you obtained with your own plot.

0
On

Tip of the day: You can focus in on a region by typing into WolframAlpha:

Plot[y^(1/y) == x, {x, 0, 5}]

Plot[y^(1/y) == x, {x, 0, 1.5}]

Plot[y^(1/y) == x, {x, 1, 1.5}, {y, 1, 20}]

... and so forth.