Section 6: Functions85
Keystrokes Display
470
 – 470 _
The weight of the water of the first (500-gram) tomato.
ENTER
 – 470

430
 – 430 _
The weight of the water in Snopes’ tomato.
XEQ
 – XEQ _ _

ALPHA
g %CH
ALPHA
 – 8.5106
Percent decrease in weight of water in Snopes’ tomato.
g CLX
 – 0

Unary of X
SIGN is a function that returns 0, –1, or 1 to the X-register depending on the value presently in X.
 If the value in X is ALPHA characters, SIGN returns 0 to X. If the value in X is less than zero (negative), SIGN returns –1 to X. If the value in X is zero, SIGN returns 1 to X. If the value in X is greater than zero (positive), SIGN returns 1 to X.
The original value of X is preserved in LAST X.
###### Trigonometric Functions
Trigonometric Modes
When you are using trigonometric functions, angles can be assumed by the HP-41C to be in decimal degrees, radians, or grads. Unless you specify otherwise with one of the trigonometric mode functions, the HP-41C assumes that angles are in decimal degrees. When you specify a trigonometric mode, the HP-41C remains in that mode until you change it, even while the HP-41C is turned off.
To select radians mode, execute the RAD (radians) function before using a trigonometric function. The RAD annunciator in the display will turn on to remind you that you are in radians mode.
To select grads mode, execute the GRAD (grads) function before using a trigonometric function. The GRAD annunciator in the display will turn on to remind you that you are in radians mode.
To select decimal degrees mode, execute the DEG (degrees) function before using a trigonometric function. Since the HP-41C normally assumes that angles are in decimal degrees, no display annunciator shows.