Re: Bug in all 85 and 86


[Prev][Next][Index][Thread]

Re: Bug in all 85 and 86



Clayton L. Workman wrote:

> dot([(2,3),(-4,6),(-2,0)],[(5,7.2),(2,-5),(-5,7)])
>
> The TI returns:   (3.6,-6.6)
>
> This is incorrect.  The correct answer is: (20.4,47.4)

I confirm this.  I also tried

dot([(1,2),(2,3)],[(2,1),(3,2)]) for which the TI returns (16,8) while the
correct response is (0,18).

Entering (1,2)*(2,1)+(2,3)*(3,2) produces (0,18).

What could it be thinking?  I try dot([(1,0),(1,0)],[(0,1),(0,1)]) and get
the correct answer, (0,2).

dot([(1,0),(1,0)],[(0,1),(0,1)]) also produced the right answer, (1,2).

However, dot([(1,0),(1,1)],[(0,1),(1,1)]) produces (2,1) instead of (0,3).

Also, dot([(1,0),(1,3)],[(0,1),(1,2)]) produces (7, 0) instead of (-5,6).

If we assume that it is correctly computing (1,0)*(0,1) = (0,1), then it
must be computing (1,3)*(1,2) = (7,-1) which looks like (a,b)*(c,d) is
coming out (ac+bd,ad-bc), instead of (ac-bd,ad+bc).

Thanks for the gem Clayton!  Now, TI, - how about reissuing the '86 with a
bug fix?

Geoff Hagopian,
Palm Desert, CA


References: