Section 11: Calculating With Complex Numbers 121

Complex mode is activated

1)automatically, when executing ´Vor ´}; or

2)by setting flag 8, the Complex mode flag (F8).

When the calculator is in Complex mode, the C annunciator in the display is lit. This tells you that flag 8 is set and the complex stack exists. In or out of Complex mode, the number appearing in the display is the number in the real X-register.

Note: In Complex mode (signified by the C annunciator), the HP- 15C performs all trigonometric functions using radians. The trigonometric mode annunciator in the display (RAD, GRAD, or blank for Degrees) applies to two functions only: ; and : (as explained later in this section).

Deactivating Complex Mode

Since Complex mode requires the allocation of five registers from memory, you will have more memory available for programming and other advanced functions if you deactivate Complex mode when you are working solely with real numbers.

To deactivate Complex mode, clear flag 8 (keystroke sequence: " 8). The C annunciator will disappear.

Complex mode is also deactivated when Continuous Memory is reset (as described on page 63). In any case, deactivating Complex mode dissolves the imaginary stack, and all imaginary numbers there are lost.

Complex Numbers and the Stack

Entering Complex Numbers

To enter a number with real and imaginary parts;

1.Key the real part of the number into the display.

2.Press v

3.Key the imaginary part of the number into the display.

4.Press ´ V. (If not already in Complex mode, this creates the imaginary stack and displays the C annunciator.)