# HG changeset patch # User Bobby Moretti <[EMAIL PROTECTED]> # Date 1179852649 25200 # Node ID 5d423d8161906a30efe1b6837524724737303db2 # Parent 82e2148257968030ef5a6d2a5ee415aaf0927f28 implemented SR.numerical_approximation()
diff -r 82e214825796 -r 5d423d816190 sage/calculus/calculus.py
--- a/sage/calculus/calculus.py Mon May 21 09:16:32 2007 -0700
+++ b/sage/calculus/calculus.py Tue May 22 09:50:49 2007 -0700
@@ -647,6 +647,47 @@ class SymbolicExpression(RingElement):
"""
return long(int(self))
+ def numerical_approximation(self, prec=53):
+ """
+ Get a numerical approximation of self as either a real or complex
+ number.
+
+ INPUT:
+ prec -- the precision (in bits), or a field in which to coerce
+
+ OUTPUT:
+ An RealNumber or ComplexNumber approximation of self with prec
bits
+ of precision.
+
+ EXAMPLES:
+ sage: cos(3).numerical_approximation()
+ -0.989992496600445
+
+ sage: cos(3).numerical_approximation(200)
+ -0.98999249660044545727157279473126130239367909661558832881409
+
+ sage: SR(i + 1).numerical_approximation(32)
+ 1.00000000 + 1.00000000*I
+
+ ALIASES:
+ numerical_aproximation and numerical_approx are the same.
+
+ """
+ # make sure the field is of the right precision
+ try:
+ field = RealField(prec)
+ except TypeError:
+ field = prec
+
+ try:
+ approx = self._mpfr_(field)
+ except TypeError:
+ # try to return a complex result
+ approx = self._complex_mpfr_field_(ComplexField(field.prec()))
+
+ return approx
+
+ numerical_approx = numerical_approximation
def _mpfr_(self, field):
raise TypeError
~Bobby
On 5/21/07, William Stein <[EMAIL PROTECTED]> wrote:
>
>
> On 5/21/07, Bobby Moretti <[EMAIL PROTECTED]> wrote:
> > In the past, we've favored polluting the class namespace over lack of
> > clarity. For example, simplify_trig = trig_simplify, simplify_rational =
> > rational_simplify, etc. Would it be so bad to have, something like:
> >
> > def numerical_approximation(self, prec):
> > try:
> > field = RealField(prec)
> > except TypeError:
> > field = prec
> > return self._mpfr_(field)
> >
> > in symbolic expression objects?
>
> Actually I like that since it's so clear. Be careful to allow
> the answer to be in ComplexField if there is no coercion
> to RealField.
>
> William
>
> >
>
--
Bobby Moretti
[EMAIL PROTECTED]
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