HP 15c Scientific Polar and Rectangular Coordinate Conversions, Complex Results from Real Numbers

Section 11: Calculating With Complex Numbers 133

Complex Results from Real Numbers

In the preceding examples, the entry of complex numbers had ensured the (automatic) activation of Complex mode. There will be times, however, when you will need Complex mode to perform certain operations on real

numbers, such as − 5 . (Without Complex mode, such as operation would result in an Error 0 – improper math function.) To activate Complex mode at any time and without disturbing the stack contents, set flag 8 before executing the function in question.*

Example: The arc sine (sin-1) of 2.404 Assuming 2.404 in the X-register, the calculated as follows:

normally would result in an Error 0. complex value arc sin 2.404 can be

KeystrokesDisplay

F 8

, 1.5708

´% (hold) -1.5239

(release)1.5708

Activates Complex Mode.

Real part of arc sin 2.404.

Imaginary part of arc sin 2.404.

Display shows real part again when %is released.

Polar and Rectangular Coordinate Conversions

In many applications, complex numbers are represented in polar form, sometimes using phasor notation. However, the HP-15C assumes that any complex numbers are in rectangular form. Therefore, any numbers in polar or phasor form must be converted to rectangular form before performing a function in Complex mode.

*Pressing ´ } twice will accomplish the same thing. The sequence ´ V is not used because it would combine any numbers, in the real X-. and Y-registers into a single complex number.