Thread Rating:
  • 2 Vote(s) - 4 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Searching for an asymptotic to exp[0.5]
I have considered many more things then I could ever post ...

I probably said it before but Im considering " fake analytic number theory ".

That might take some time to develop.

Here are some other ideas that inspire me and for which Im currently not sure how to continue.

---

Jay's function that approximates the binary partition function has become popular here.

I wonder about variants of type

DO these variants of " cubic type " solve anything ?

---

***

Initially fake function methods start with an OVERESTIMATE.

It is possible to use a method that is both GOOD and starts with an UNDERESTIMATE ?

***

###

Im wondering about fake fourier series and fake integrals.

A logical way , but possibly not the best , is to consider the fake function methods as fake n'th derivatives.

Then the fake integral is computed as the fake first derivative of the true second integral.

Or something like that ...

###

|||

Lets try Jay's function J(x).

a_n x^n = J(x)

ln(a_n) + n ln(x) = ln(J(x))

ln(a_n) = min[ ln(J(x)) - n ln(x) ]

d/dx [ ln(J(x)) - n ln(x) ] = J(x/2)/J(x) - n/x

J(x/2)/J(x) = n/x

I really like the shape of this equation.
And ofcourse I wonder how good a_n will be compared to

ALthough Im not completely stuck here , Im also not completely sure how to proceed.
Use asymptotics , invent new special function , use contour integrals , numerical methods , ... ?

@@@

Under some trivial conditions I consider some ideas to improve finding a fake function without actually changing the method ...

example

Find fake exp(x).

Note : We already discussed the idea that we already have an entire function with positive derivatives , yet this is intresting.
And just an example , it applies to non-entire functions too.

Instead of
a_n x^n = exp(x)

We solve for

a_n x^n = 2 exp(x) / (1+x)

Then we multiply our result (taylor series with a_n , possibly scaled ) with (1+x)/2.

Notice multiplication by (1+x)/2 does not change the signs of the derivatives and is easy to compute !

The q-variant of this is also possible of course.

I call these methods

sx9(n) and qx9(n).

So for instance

Much more work needs to be done !

@@@

Comments and help is appreciated.

regards

tommy1729

" Formally define useful and useless , but beware : take into account we are plain mortals and your an atheist who claims to be not obsessed by money nor by ego "
tommy1729 @sci.math
Reply


Messages In This Thread
RE: Searching for an asymptotic to exp[0.5] - by tommy1729 - 11/07/2014, 12:27 AM

Possibly Related Threads...
Thread Author Replies Views Last Post
  Merged fixpoints of 2 iterates ? Asymptotic ? [2019] tommy1729 1 586 09/10/2019, 11:28 AM
Last Post: sheldonison
  Another asymptotic development, similar to 2sinh method JmsNxn 0 2,559 07/05/2011, 06:34 PM
Last Post: JmsNxn



Users browsing this thread: 1 Guest(s)