HP 48g Graphing Calculator - Manual (Page 155)

Real Calculations with Complex Results
The coinpiex-number capabilities of the HP 48 can affect the results
of real-number operations. Certain calculations that would result in
an error on most calculators yield valid complex results on the HP 48.
For example, the HP 48 returns a complex number for the square root
of “4. Also, the arcsine of 5 yields a complex result.
You’ll find that for most calculations, the HP 48 gives you the type of
result (real or complex) you expect. However, if you find that you get
complex results when you expect real results, check your program or
keystrokes for these potential causes:
■ The data you supplied to the calculator may be outside the range of
the formula you are calculating.
■ The formula (or its execution) may be incorrect.
■ A rounding error at a critical point in the formula may have
compromised the computation.
■ A complex result may be unexpected, but correct, for your problem.
12
Other Complex-Number Commands
Most commands that operate on real numbers also operate on complex
numbers (such as SIN, INV, and LN). The following table describes
additional commands that are especially useful for complex numbers.
The remaining commands are found in the MTH CMPL menu (press
fMTH ) fNXT) C M P L .
Command / Description
Example
Input Output
ABS Prefix. Absolute
value; ^.
i - ( E= :i 4 ) is 5
ARG Prefix. Polar angle of
a complex number.
i s
< 1
5
1 ) is 45
CONJ Prefix. Complex
conjugate of a complex
number.
is ( 2 , 3 ) i s < 2 ? - 3 >
Functions of Real and Complex Numbers 12-13