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The calculator provides the function IFTE (IF-Then-Else) to describe such
functions.
The IFTE function
The IFTE function is written as
IFTE(condition, operation_if_true, operation_if_false)
If condition is true then operation_if_true is performed, else operation_if_false
is performed. For example, we can write ‘f(x) = IFTE(x>0, x^2-1, 2*x-1)’, to
describe the function listed above. Function IFTE is accessible from the
function catalog (‚N). The symbol ‘>’ (greater than) is available as
(associated with the Y key). To define this function in ALG mode use the
command: DEF(f(x) = IFTE(x>0, x^2-1, 2*x-1))
then, press `. In RPN mode, type the function definition between
apostrophes:
‘f(x) = IFTE(x>0, x^2-1, 2*x-1)’
then press „à.
Press J to recover your variable menu. The function @@@f@@@ should be
available in your soft key menu. Press ‚@@@f@@@ to see the resulting program:
<< x ‘IFTE(x>0, x^2-1, 2*x-1)’ >>
To evaluate the function in ALG mode, type the function name, f, followed by
the number at which you want to evaluate the function, e.g., f(2), then press
`. In RPN mode, enter a number and press @@@f@@@. Check, for example,
that f(2) = 3, while f(-2) = -5.
Combined IFTE functions
To program a more complicated function such as
≥
<≤−
<≤−+
−<−
=
2,
20,1
02,1
2,
)(
2
xx
xx
xx
xx
xg
you can combine several levels of the IFTE function, i.e.,
‘g(x) = IFTE(x<-2, -x, IFTE(x<0, x+1, IFTE(x<2, x-1, x^2)))’,
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