how can i solve x/ln(n)=100

danielhaish

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Hi i am worikng on some encryption program and i need to solve this problem thereis any chance thus is possible using w Limburg function and how
 

Subhotosh Khan

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Hi i am worikng on some encryption program and i need to solve this problem thereis any chance thus is possible using w Limburg function and how
The expression in the subject line

x/lenx=n

does not make any sense to me. Please "correct" it and re-post.
 

danielhaish

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The expression in the subject line

x/lenx=n

does not make any sense to me. Please "correct" it and re-post.
is it ok now i just need alitle help in solving this kind of problem
 

Subhotosh Khan

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Harry_the_cat

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What is "len"?
 

danielhaish

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I am sory I meant ln
 

danielhaish

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i cant edit it right now from some reason
so this is the equation x/ln(x)=n
 

MarkFL

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I would use the function:

\(\displaystyle f(x)=x-n\ln(x)=0\)

And use the Newton-Raphson method to recursively find the root to a desired accuracy.
 

danielhaish

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hi i olso got something like that but cant solve it
nt-e^t=0
I would use the function:

\(\displaystyle f(x)=x-n\ln(x)=0\)

And use the Newton-Raphson method to recursively find the root to a desired accuracy.
in the end i simplified it to 100t-e^t while t=len(x)
and i use regula falsi method tenx
 

HallsofIvy

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To solve \(\displaystyle \frac{x}{ln(x)}= n\) for x, write it as \(\displaystyle \frac{ln(x)}{x}= \frac{1}{n}\) and let y= 1/x. The equation becomes \(\displaystyle y ln(1/y)= -y ln(y)= \frac{1}{n}\) or \(\displaystyle y ln(y)= -\frac{1}{n}\). NOW you can use Lambert's W function that I think you intended in your first post: \(\displaystyle y= W\left(-\frac{1}{n}\right)\) and then \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
 

danielhaish

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To solve \(\displaystyle \frac{x}{ln(x)}= n\) for x, write it as \(\displaystyle \frac{ln(x)}{x}= \frac{1}{n}\) and let y= 1/x. The equation becomes \(\displaystyle y ln(1/y)= -y ln(y)= \frac{1}{n}\) or \(\displaystyle y ln(y)= -\frac{1}{n}\). NOW you can use Lambert's W function that I think you intended in your first post: \(\displaystyle y= W\left(-\frac{1}{n}\right)\) and then \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
tenx it make my program alot more simple becuase now i just use function that allready exsits
 

danielhaish

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To solve \(\displaystyle \frac{x}{ln(x)}= n\) for x, write it as \(\displaystyle \frac{ln(x)}{x}= \frac{1}{n}\) and let y= 1/x. The equation becomes \(\displaystyle y ln(1/y)= -y ln(y)= \frac{1}{n}\) or \(\displaystyle y ln(y)= -\frac{1}{n}\). NOW you can use Lambert's W function that I think you intended in your first post: \(\displaystyle y= W\left(-\frac{1}{n}\right)\) and then \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
hi i tried possed n=10 and then take the x and poss it in education and it doesn't return 10 it return 4
 
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