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Question: Does anyone can explain the evaluation rules for "evalf"?

Question:Does anyone can explain the evaluation rules for "evalf"?

mmcdara 6740 Maple 2015
evalf
January 20 2018
0

Hi,

I am a little bit surprised by the result of the operation evalf[8](f(y)) in the piece of code that follows.
I was expected the answer to be 2.4494897, not 2.4494898.

Happily the sequence
res := f(y) ; evalf[8](res)
returns the expected result 2.4494897

I suspect the difference comes from some precedence of the operators (f and evalf) but I can't figure out what really happens

Could you enlight me please ?

Thanks in advance

 

> 

restart:
> 

interface(version);

`Standard Worksheet Interface, Maple 2015.2, Mac OS X, December 21 2015 Build ID 1097895`

 (1)
> 

Digits;

10

 (2)
> 

f := x -> sqrt(2.0)*x;

proc (x) options operator, arrow; sqrt(2.0)*x end proc

 (3)
> 

y := sqrt(3.0):
> 

f(y);

2.449489743

 (4)
> 

evalf[9](f(y));  # right

2.44948974

 (5)
> 

evalf[8](f(y));  # ????

2.4494898

 (6)
> 

res := f(y);
evalf[8](res);  # right

2.449489743

  

2.4494897

 (7)
> 

 

 

 
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