TI-92 Bug


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TI-92 Bug



-=> Peter Maigaard conveyed this to TI-Calc on 07-16-97  10:03 <=-

 In> Hi,

 In> I think I may have found a bug in the TI-92 when calculating with
 In> complex numbers in polar format, in degree mode. (No error occurs in
 In> radian mode).
[snip]

Thank you _very_ much for posting this.  I too am an electrical
engineer and depend on complex arithmetic, although I spend much
of my time doing boring paperwork.

It appears as though when you have mode set to ANGLE, complex
exponents are still interpretted as radian.  If you want the 35 in
2*e^(35i) to be degrees, include the degree symbol by pressing
2nd-D between the 5 and the i.  This will give you the expected
result.

Alternatively you can use polar notation.  Your 2*e^(35i) would
be: [2, <35] where the symbol < is available by pressing 2nd-CHAR,
2:Math, 8:.  Unfortunately I've heard that complex numbers
represented in polar form have to be converted to rectangular
form before division and multiplication (and I guess exponentiation)
can be performed.

Myself, I try always to work in rectangular form since e^(x*i)
is a vector with an angular velocity.  When we use polar form
to represent an impedance, we're really mis-using mathematics.

                   Raymond Zeitler, Design Engineer

     Phonon Corp.  90 Wolcott Road, PO Box 549, Simsbury CT 06070
                 TEL 860-651-0211   FAX 860-651-8618

r.zeitler@ieee.org