Re: [foxboro] AGA8 or cubic root in HLBL code

I recently ran into this same problem. Originally I had used the MATH block
but this solution was too klunky for my application.

I implemented the exponential function directly in the IND block by creating
a subroutine which approximates the exponential function as a series.

 X            X      X*X    X*X*X
e   = 1  +  -   +  -   +    -     ....
            1!     2!       3!

A similar expansion can be used for 10^X. I had to use 17 terms to get the
accuracy I needed. Not perfect but it seems to work.


> -----Original Message-----
> From: foxboro-bounce@xxxxxxxxxxxxx
> [mailto:foxboro-bounce@xxxxxxxxxxxxx]On Behalf Of Jeremy Milum
> Sent: Friday, October 21, 2005 8:56 PM
> To: foxboro@xxxxxxxxxxxxx
> Subject: Re: [foxboro] AGA8 or cubic root in HLBL code
>
>
> On 10/21/05, brad.s.wilson@xxxxxxxxxxxxxx
> <brad.s.wilson@xxxxxxxxxxxxxx> wr=
> ote:
> > I see basic 4-function calculator operators, modulus, logic and
> relationa=
> l
> > operators ... but no exponential operator.
> > Surely I'm overlooking it ... right?
>
> no. it's not there...
>
> > I see the CALC block can do logarithms and exponentials.
>
> yes and if you need to do those things in a sequence block you have to
> use a calc block for assistance, very kludgy but it will work.
>
> > (Obviously, I've never had a need to do this.)
>
> I have and it is demoralizing :( I have brought this up repeatedly at
> the User's Group, but I have been told that it cannot and will not
> ever be fixed. HLBL is all it is.... Now you could use the
> Newton-Raphson method to iteratively calculate a cube root, but it
> would be better to just us a calc block and tie that into the seq
> block.
>
> --
> Patron saints in general are broadband connections to the Almighty
> - Michelle Delio, Wired News
>
>
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