Re: Bug in all 85 and 86
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Re: Bug in all 85 and 86
Perhaps the following will shed some light on this.
The following results using Maple V Release 4:
>with(linalg):
Warning, new definition for norm
Warning, new definition for trace
> u :=vector([2+3*I,-4+6*I,-2+0*I]);
u := [2 + 3 I, -4 + 6 I, -2]
> v :=vector([5+7.2*I,2-5*I,-5+7*I]);
v := [5. + 7.2 I, 2 - 5 I, -5 + 7 I]
> dotprod(u,v);
3.6 + 6.6 I
dotprod computes the vector dot product using the standard definition for a
vector space over the complex field: sum u[i]*conjugate(v[i]), as i ranges
over the length of u and v.
>crossprod(u,v);
[-18 - 68 I, 21. - 13.4 I, 82.2 - 5.2 I]
crossprod computes the vector cross-product of u and v, defined to be
vector([u[2]*v[3]-u[3]*v[2], u[3]*v[1] u[1]*v[3], u[1]*v[2] u[2]*v[1]]).
>innerprod(u,v);
20.4 + 47.4 I
innerprod calculates the inner product of a sequence of vectors and
matrices.
>
The TI-92 gives the same results for the dotp and crossp. The function
innerprod
is not on the TI-92.
The TI-85/86 agrees with the cross product. What is of concern is that the
TI-85/86 produces 3.6-6.6i (sign difference) for the dot product.
------------------------------------------------------------------
Ben Sultenfuss <bsultenfuss@sfasu.edu>
Stephen F. Austin State University
Department of Mathematics and Statistics
1936 North Street
PO Box 13040, SFA Station
Nacogdoches, Texas 75962-3040
Phone: Office: 409-468-3805 Home: 409-560-5508
Fax: Office: 409-468-1669 Home: 409-560-0038
----------
> From: Clayton L. Workman <cworkman@RAIDER.CRSC.K12.AR.US>
> To: CALC-TI@LISTS.PPP.TI.COM
> Subject: Bug in all 85 and 86
> Date: Sunday, August 31, 1997 04:03
>
> A colleague and I have found a bug in the TI 85 (ROMS 8,9,10) and 86
> (ROM 1.2) with the dot product of two complex vectors.
>
> Now, complex vectors aren't used very often by many of the people who
> use TI's, I assume. I also assume that this is the reason that I
> haven't heard about this bug. Perhaps it hasn't been discovered.
>
> Take this command for example:
>
> dot([(2,3),(-4,6),(-2,0)],[(5,7.2),(2,-5),(-5,7)])
>
> The TI returns: (3.6,-6.6)
>
> This incorrect. The correct answer is: (20.4,47.4)
>
> Try any combination of complex vectors.
>
> I thought I would bring this to the attention to you folks especially to
> those EE's out there who may need this function to work correctly.
>
> Anyway, I'm going back to the HP48GX. It can do it correctly. (Among
> having a lot of other additional and nicer features.) So if there's
> anyone out there who care's nothing for this bug and would like to
> purchase my 86, then contact me and make an offer. It's in excellent
> shape since I just bought it a month ago. I just can't live with this
> bug.
>
> Thanks.
>
> Clayton Workman
> cworkman@raider.crsc.k12.ar.us