Revision history [back]
 | 1 | initial version |
FWIW :
sage: x = -5564456128*e + 15125759978
sage: (x-1/47749).n(digits=50)
2.2327547500435249115043756744718383299006623385945e-10
As usual, stay exact as long as possible... The chapters of this book dedicated to numerical computation may enlighten you...
Note that a "visual" comparison based on :
sage: "%8.6g, %8.6g"%(x,1/47749)
'2.09808e-05, 2.09428e-05'
misses the target by about two magnitude orders (implying a difference of about 4e-8...).
Note also that :
sage: (x-1/47749).is_zero()
False
sage: (x-1/47749).is_positive()
False
sage: (x-1/47749).is_negative()
False
which is surprising, but conformant to the definitions of the methods : nothoing is known nor deducible about these quantities, and only numerical computation of their differences allows to answer the question.
