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

D

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
 
danielhaish said:
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
Click to expand...
The expression in the subject line

x/lenx=n

does not make any sense to me. Please "correct" it and re-post.
 
I would use the function:

[MATH]f(x)=x-n\ln(x)=0[/MATH]
And use the Newton-Raphson method to recursively find the root to a desired accuracy.
 
hi i olso got something like that but cant solve it
nt-e^t=0
MarkFL said:
I would use the function:

[MATH]f(x)=x-n\ln(x)=0[/MATH]
And use the Newton-Raphson method to recursively find the root to a desired accuracy.
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in the end i simplified it to 100t-e^t while t=len(x)
and i use regula falsi method tenx
 
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 \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
 
HallsofIvy said:
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 \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
Click to expand...
tenx it make my program alot more simple becuase now i just use function that allready exsits
 
HallsofIvy said:
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 \(\displaystyle x= \frac{1}{W\left(-\frac{1}{n}\right)}\).
Click to expand...
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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