Changeset 7634:fb4045978e5b

Timestamp:

12/13/07 10:38:31 (5 years ago)

Author:

William Stein <wstein@…>

Branch:

default

Message:

Fix trac #1489 -- bug doing symbolic computations with certain small numbers -- reported by Matthias Hillenbrand.

File:

• sage/calculus/calculus.py (modified) (3 diffs)

sage/calculus/calculus.py

@@ -196 +196 @@
     5
 
+Simplifying expressions involving scientific notation:
+    sage: k = var('k')
+    sage: a0 = 2e-6; a1 = 12
+    sage: c = a1 + a0*k; c
+    2.000000000000000e-6*k + 12
+    sage: sqrt(c)
+    sqrt(2.000000000000000e-6*k + 12)
+    sage: sqrt(c^3)
+    (2.000000000000000e-6*k + 12)^(3/2)
+
 The symbolic Calculus package uses its own copy of Maxima for
 simplification, etc., which is separate from the default system-wide
@@ -235 +245 @@
                             PolynomialRing, ComplexField,
                             algdep, Integer, RealNumber)
+
+from sage.rings.real_mpfr import create_RealNumber
 
 from sage.structure.element import RingElement, is_Element
@@ -5982 +5994 @@
         s = s.replace('=','==')
 
-    #replace all instances of scientific notation
+    #replace all instances of Maxima's scientific notation
     #with regular notation
     search = sci_not.search(s)
     while not search is None:
         (start, end) = search.span()
-        s = s.replace(s[start:end], str(RR(s[start:end])))
+        r = create_RealNumber(s[start:end]).str(no_sci=2, truncate=True)
+        s = s.replace(s[start:end], r)
         search = sci_not.search(s)