The Rounding Environment Variable

Calling Sequence


Rounding := x


Parameters


x



one of 0, nearest, infinity, infinity, simple





Description


•

The Rounding environment variable controls the rounding of floatingpoint results.

•

There are five rounding modes available in Maple.

Rounding Mode

Meaning



nearest

round to the nearest possible value,


with ties resolved by rounding to the nearest even

0

round towards zero

infinity

round towards positive infinity

infinity

round towards negative infinity

simple

round to the nearest possible value,


with ties resolved by rounding up





•

The value of Rounding is changed by using the assignment operator. The default value of Rounding is nearest.

•

To determine the current value of Rounding during a Maple session, enter the command Rounding;.

•

The rounding mode determines the sign of 0 when it cannot be obtained otherwise.

•

Infinities always round to themselves, independent of the rounding value.

•

Maple fully evaluates environment variables such as Rounding. Because Rounding is an environment variable, any assignments to it inside a procedure body are undone upon exit from the procedure.



Examples


>

f := proc()
print( "Entering f. Rounding is", Rounding );
Rounding := infinity;
print( "The current value of Rounding is", Rounding );
end proc:

${''Entering\; f.\; Rounding\; is''}{\,}{\mathrm{nearest}}$
 
${''The\; current\; value\; of\; Rounding\; is''}{\,}{}{\mathrm{\∞}}$
 (2) 
When returning from f in the procedure above, Maple resets Rounding to its value on entry to f.
>

$\mathrm{Rounding}\u22540$

${\mathrm{Rounding}}{\u2254}{0}$
 (5) 
>

$\mathrm{Rounding}\u2254\mathrm{nearest}$

${\mathrm{Rounding}}{\u2254}{\mathrm{nearest}}$
 (7) 
>

$\mathrm{Rounding}\u2254\mathrm{\∞}$

${\mathrm{Rounding}}{\u2254}{}{\mathrm{\∞}}$
 (9) 






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