AnsweredAssumed Answered

vrf Complex Exponentiation : VEE Formula vs. MATLAB Scr

Question asked by VRFuser on Jan 5, 2003
Thanks, Edward and Bill. Now that we're back from our enforced 2-week vacation, I have received Bill's defect report and will verify and submit it for R&D to look at.

Thank you for a very complete and understandable report, Bill.

Vrf-ers, when you find a defect, please use the "Report a Software Defect" form found under the "Support" link in ADN Basic and Pro. You can register for ADN at < www.agilent.com/find/adn >. ADN Basic is free.

You can also submit enhancement requests with that form.

Note that we don't normally individually acknowledge submissions made with that form; the workload would be too great. But since this came up on the vrf, and the vrf is special, I decided to acknowledge. I was only able to do it this time because our workload is low right now, but normally, we would not even respond on the vrf.

Hope everyone is having a great New Year.

Sincerely,


Scott Bayes
Software Technical Support

Agilent Technologies, Inc.
815 14th Street S.W.
Loveland, CO, U.S.A. 80537

970 679 3799 Tel
970 635 6867 Fax

> -----Original Message-----
> From: bill.ossmann@philips.com [mailto:bill.ossmann@philips.com]
> Sent: Monday, December 30, 2002 8:47 AM
> To: VEE vrf
> Subject: [vrf] Re: Complex Exponentiation : VEE Formula vs. MATLAB
> Script
>
>
> Very curious!
>
> I see the behavior you describe, and I'll add the following
> observations:
>
> (0,1)^(a+bi) appears to work properly except for the cases
> when abs(b)==1 and abs(a)<~1.9e-8
>
> (0,1)^Z appears to work properly if Z is an array containing
> (0,1). This could give you a workaround, since even
> (0,1)^[(0,1)] works correctly.
>
> We have validated a number of VEE programs against the same
> calculations in MATLAB (not script) and gotten excellent results.
>
> Regards,
> --
> Bill Ossmann
> Philips Ultrasound
>
>
>
>
>
>
>
>
>
>                                                    To:   "VEE
> vrf" <vrf@it.lists.it.agilent.com>
>
>                                                    cc:
> (bcc: Bill Ossmann/ANR/MS/PHILIPS)
>
>                                                    Subject:
>  [vrf] Complex Exponentiation : VEE Formula vs. MATLAB Script
>
>
>
>
>                "Edward Poncin"
> Classification:
>
>                <ed_poncin@hotmail.com>
>
>
>
>
>
>                12/27/2002 11:49 AM
>
>
>                Please respond to
>
>
>                "Edward Poncin"
>
>
>
>
>
>
>
>
>
>
>
>
>
>    COMPLEX EXPONENTIATION : VEE FORMULA vs. MATLAB Script
>
> I reported this error to Agilent some months ago. I was running
> VEE in a WINDOWS environment. There is an interesting but
> somewhat obscure equation, in which the complex operator 'i' is
> raised to the power of itself. In computerese, this is :  (i^i ).
> With pencil-and-paper methods it is easily proven to be :
>
>               exp (-PI/2 ) = 0.2079 ( approx ).
>
> When I use the VEE Formula object to calculate this complex
> exponential, the result is given as ( 0, 1 ) --> meaning 'i',
> which is WRONG.
>
> When I use the MATLAB script to assess the same quantity,
> the numerical value is given as 0.2079, which is correct to the
> number of decimal places chosen.
>
> A closely related equation occurs when the natural logarithm of
> each side is taken. Pencil-and-paper methods yield :
>
>                         i * ln(i) = ( -PI/2 )
>
> Oddly enough, the VEE Formula object yields the correct answer
> for this calculation. MATLAB handles it correctly, also.
>
>   Has anyone else encountered large discrepancies between results
> of the VEE Formula and MATLAB script ?
>
>                                           Ed Poncin
>
>
>
>
>
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