On Fri, Mar 13, 2009 at 3:19 PM, hpon <peter.norli...@gmail.com> wrote:
>
> Hi,
>
> How do I get a numerical value?
>
> I have a multi-parameter function where all the parameters have been
> substituted by numerical values. I want Sage to calculate the
> expression's numerical value. At the moment Sage prints:
>
> 1/sqrt((sqrt(3)/2 - 0.0173205080757)^2 - 0.0001) - "and so on"
>
Do you know how to use the documentation?
For example, in the notebook, I write : a = sqrt(3)
Then, a.<tab> gives me the list of methods available... and you can
find numerical_approx which sounds to be what you want...
and if you want details of a specific method, just add a question mark
at the end. For example:
a.numerical_approx?
***************************************************
Type: <type 'instancemethod'>
Definition: a.numerical_approx(prec, digits)
Docstring:
Return a numerical approximation of self as either a real or
complex number with at least the requested number of bits or
digits of precision.
NOTE: You can use foo.n() as a shortcut for
foo.numerical_approx().
INPUT:
prec -- an integer: the number of bits of precision
digits -- an integer: digits of precision
OUTPUT:
A RealNumber or ComplexNumber approximation of self with
prec bits of precision.
EXAMPLES:
sage: cos(3).numerical_approx()
-0.989992496600445
Use the n() shortcut:
sage: cos(3).n()
-0.989992496600445
Higher precision:
sage: cos(3).numerical_approx(200)
-0.98999249660044545727157279473126130239367909661558832881409
sage: numerical_approx(cos(3), digits=10)
-0.9899924966
sage: (i + 1).numerical_approx(32)
1.00000000 + 1.00000000*I
sage: (pi + e + sqrt(2)).numerical_approx(100)
7.2740880444219335226246195788
***************************************************
After reading the details, you know you can also use the n() shortcut ;)
Hope you will find the answer to your next question by yourself ;)
Best,
--
Johan
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