- #1
Count Iblis
- 1,863
- 8
Find a function [tex]f\left(z\right)[/tex] such that [tex]f\left(f\left(z\right)\right) = \exp\left(z\right)[/tex]
Galileo said:Yeah, so it doesn't work out right. It was meant as a joke anyway, hope that was obvious.
coomast said:No, it wasn't obvious. I'm upset and will not come back to this tread. You know how much time I spent on it? What were you thinking? Let's pull the stupid belgian's leg? How do think Count Iblis is feeling when he finds out his question is not taken serious?
d_leet said:eln(x)=x, so eln(x)+2a=xe2a
Zurtex said:Bah, I realized my whole method was fundamentally boring anyway, in more simplified way this is what I was trying to do:
f(x) = ea
f(f(x)) = ea
For each point let x = a
d_leet said:I don't think this makes sense, or at least it doesn't make sense to me as an answer for the question the OP posed.
christianjb said:Can it be done using Taylor series?
2 terms
f(x)=a+bx
f(f(x))=a+b(a+bx)=1+x -> a=1/2 b=1
3 terms
f(x)=a+bx+cxx
ff(x)=a+b(a+bx+cxx)+c(a+bx+cxx)^2
=(a+ba+caa)+(bb+2abc)x+(bc+2acc+bbc)xx+(2bcc)xxx+(ccc)xxxx
a+ba+caa=1.
bb+2abc=1
bc+2acc+bbc=1/2!
2bcc=1/3!
ccc=1/4!
Overdefined?- 3 unknowns/4 eqns.
The purpose of this is to find a function that satisfies a specific mathematical property. In this case, the property is that the function composed with itself (f(f(z))) equals the exponential function (exp(z)). This can be useful in solving certain mathematical equations or in understanding the behavior of complex functions.
No, there may be multiple functions that satisfy this property. However, there are some restrictions on what the function can be, such as it must be an analytic function. Additionally, some functions may be more useful or relevant in certain contexts than others.
There is no one definitive method for finding such a function, as it often involves trial and error and knowledge of complex functions. One approach is to start with a known function and manipulate it algebraically to see if it satisfies the property.
Yes, this property can be extended to other functions. For example, there are functions that satisfy the property f(f(z)) = sin(z) or f(f(z)) = z^2. However, the specific function that satisfies the property may be different for each function.
This property may not have direct applications in the real world, but it is a fundamental concept in mathematics and can be used in various mathematical equations and proofs. It can also help in understanding the behavior of complex functions and their compositions.