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Section 6: Functions 85
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Unary of X
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SIGN is a function that returns 0, –1, or 1 to
the X-register depending on the value presently in X.
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If the value in X is ALPHA characters, SIGN
returns 0 to X.
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If the value in X is less than zero (negative), SIGN
returns –1 to X.
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If the value in X is zero, SIGN
returns 1 to X.
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If the value in X is greater than zero (positive), SIGN
returns 1 to X.
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The original value of X is preserved in LAST X.
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Trigonometric Functions
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Trigonometric Modes
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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.
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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.
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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.
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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.
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