HP 50g User Manual page 697

IF x<3 THEN
2
x
ELSE
1-x
END
While this simple construct works fine when your function has only two
branches, you may need to nest IF...THEN...ELSE...END constructs to deal with
function with three or more branches.
Here is a possible way to evaluate this function using IF... THEN ... ELSE ...
END constructs:
IF x<3 THEN
2
x
ELSE
IF x<5 THEN
ELSE
END
END
⎧
⎪
⎪ ⎪
f ( x )
⎨
3
⎪
⎪
⎪
⎩
1-x
IF x<3
sin(x)
ELSE
IF x<15 THEN
ELSE
END
END
For example, consider the function
2
x , if x
1 x , if 3
sin( x ), if 5
exp( x ), if 3
, 2 elsewhere
THEN
exp(x)
-2
3
x 5
x 3
x 15
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