Re: TI-92 Phasor question
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Re: TI-92 Phasor question
You can sove the problemm buy pressing [2nd] D, this will print the
degree sysmbol, this forseds the calulator to accept it as degrees, as
least it should work.....
-Paul Bruner
On Thu, 24 Oct 1996 rschatz@ELE.KTH.SE wrote:
> Congratulations, you have discovered a bug that occurs when you are
> using complex notation in degree format (which I by the way would
> avoid since it is so uncommon). Here is an explanation of the bug.
>
> Apparently the 92 interpret the input as radians (despite the degree
> mode setting), simplifies it, and then converts the simplified value
> to degrees at output.
>
> When you input
>
> e^(-70.0*i)
>
> and try to store it in variable b, the calculator interprets it as
> radians and simplifies it to
>
> e^(-70.0*i)=e^((-70.0+22*Pi)*i)=e^(-0.8849616*i)
>
> Then it converts
>
> -0.8849616 radians=-0.8849616*180/Pi degrees=-50.7045659157 degrees
>
> The expression e^(-50.70456*i) is stored in the variable b
>
> When you type b it interprets the argument again as radians and
> simplifies it
>
> e^(-50.70456*i)=e^((-50.70456+16*Pi)*i)=e^(-0.43908345*i)
>
> Then it converts
>
> -0.43908345 radians=-0.43908345*180/Pi degrees=-25.157629 degrees
>
> and gives e^(-25.157629*i) as output.
>
> It is easier to follow the bug if you instead use a fraction of Pi
> as an input.
>
> This is a rather serious bug that must be corrected in future ROM
> versions (I have version 1.11) so it is good that you have reported
> the problem to TI.
>
> Richard Schatz
> Laboratory of Photonics and Microwave Eng.
> Royal Institute of Technology
> Stockholm
>
> Randall Vogtman wrote:
> > While performing phasor (Steinmetz) calculations with my new TI-92, I've
> > come across a problem where I don't believe a variable is storing
> > correctly.
> > I've sent a question off to ti-cares, but I thought I'd try here also.
> >
> > i = [2nd] I (imaginary i) not the letter
> > e = [2nd] LN e(x) (natural logarithm)
> >
> > First I define b as a -70.0 degree polar phasor value; Enter:
> >
> > define b=e(-70.0i)
> >
> > Then I try to examine the variable by entering b; the calculator
> > returns:
> >
> > e -25.1576E0i (superscript)
> >
> > These are not equal.
> >
> > Calculator Modes:
> > Complex format - Polar
> > Angle - Degree
> > Exact/Approv - Auto
> >
> > I've tried various combinations of formats and modes and I've discovered
> > the following parameters:
> >
> > Exclusion of the decimal point, b=e(-70i), will store correctly, the
> > decimal point seems to confuse it.
> >
> > Exclusion of i (imaginary) will cause the calculator to return the
> > computed value (397.545E-33) which is understandable, although I'd like
> > to see the e retained, like pi.
> >
> > Has anyone seen this before and maybe point me in the right direction?
> >
> > Thanks,
> >
> > shamaal@iwl.net
>
References: