Exp of complex numbers?

[cidadao]

Hello,

Why ti89-titanium doesn't accept exponencials of complex numbers?
As a consequence, we can't calculate cosh of complex numbers, right?

This is intriguing me because Im trying to do the same thing in an old casio calculator (fx 1.0plus) and I have no problem. In that calc, I can also calculate cosh(x) by definition: 1/2 (e^(x) + e^(-x))

Also, Im trying this:

sqrt((0,0773 + i*0,428) /2,687E-6) = ?

The correct answer is: 402.15 < -5.12º (casio)
But on my TI89 I get: 402.32 < 39.88º (TI-89)

("<" means "angle")

Am I doing something wrong?

Thanks in advance for you time.

[BlainUSM]

The TI-89 DOES calculate both e^(a + bi) and cosh(a + bi) , where a and b are real numbers. You may be (incorrectly) using the character “i” in place of the complex number i. To access the complex number i push “2nd” and then “CATALOG”. Here’s an example.

Calculate e^(pi*i) by pushing

1. the green key with a black diamond
2. the “X” key to access “e^(”
3. the blue “2nd” key
4. the “^” key (to access pi)
5. the blue “2nd” key
6. the “CATALOG” key.
7. the “)” key
8. the “ENTER key

Your output should be -1. To calculate cosh(pi*i) = e^(pi*i) = -1, type “cosh(“ in step 2 in the above key sequence.