OpenEuphoria

Re: Implementation of exp()

• Posted by Al Getz <Xaxo at aol.c??> Aug 28, 2007
• 582 views

CChris wrote:
> 
> Al Getz wrote:
> > 
> > Hi there,
> > 
> > 
> > If you dont like the results of power(e,x) then the only alternative
> > is to implement your own power series.  Taylors is the most popular
> > and easy to implement, so maybe start there and check the accuracy
> > of that and compare with power(e,x).
> > Most of the time when i use exp(x) i implement as power(e,x) unless
> > i need better accuracy then i go to a big number routine, but
> > either way i end up using x negative because that comes up so much
> > more in time domain studies of electrical networks and even networks
> > that represent other physical processes.
> > 
> > Example:
> >   y=a*exp(-t/b)
> > where t is time and a,b are constants depending on circuit values
> > and b is almost always positive.
> > 
> > 
> > Al
> > 
> > E boa sorte com sua programacao Euphoria!
> > 
> > 
> > My bumper sticker: "I brake for LED's"
> > 
> 
> No need for such efforts, the standard C library has done it way before us.
> It has a native exp() function, which I checked against arbitrary precision
> computation: the native exp() doesn't have issues, only power(E,x) has. And
> i is not because the value of E is inexact - things are ok as long as x is no
> greater than 7 or something.
> 
> The implementation would duplicate the code for sin(), with a check for
> overflow
> (the maximum allowable value for x is 1024*ln(2), which is about 694).
> 
> CChris
> 
> CChris


You mean only the Euphoria version of power(e,x) doesnt work
right?


Take care,
Al

E boa sorte com sua programacao Euphoria!


My bumper sticker: "I brake for LED's"

 From "Black Knight":
"I can live with losing the good fight,
 but i can not live without fighting it".
"Well on second thought, maybe not."