1.090516455488E9 / 1000000.000 ???

[Math]

Hello,

I got a simple and probably stupid newby question..
When I compute:
1.090516455488E9 / 1000000
the result is 1090516455.49
Should be 1090516455.488

I know something with float and //...

Anybody?
How do I get correct number?

[Georg Brandl]

Math wrote:

Hello,

I got a simple and probably stupid newby question..
When I compute:
1.090516455488E9 / 1000000
the result is 1090516455.49
Should be 1090516455.488

I know something with float and //...

Anybody?
How do I get correct number?

Python 2.4.2 (#1, Mar 12 2006, 00:14:41)
[GCC 3.4.5 (Gentoo 3.4.5-r1, ssp-3.4.5-1.0, pie-8.7.9)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

1.090516455488E15 / 1000000 1090516455.4879999 print 1.090516455488E15 / 1000000

1090516455.49

print is using str() which formats the float number with 12 digits
precision and therefore rounds the result.
repr() however, which is used by the interpreter when printing
out expression results, uses 17 digits precision which is why
you can see how the result is stored in the computer's memory
(1090516455.487999999999999....).

Georg

[Nick Craig-Wood]

Math <ma*********@home.nl> wrote:

I got a simple and probably stupid newby question..
When I compute:
1.090516455488E9 / 1000000
the result is 1090516455.49
Should be 1090516455.488

I know something with float and //...

http://www.python.org/doc/faq/genera...-so-inaccurate

Eg

a=1.090516455488E9 / 1000000
print a 1090.51645549 print repr(a) 1090.516455488
If you want a given number of decimal places you can use a formatter,
eg
print "%.20f" % a

1090.51645548800001961354

--
Nick Craig-Wood <ni**@craig-wood.com> -- http://www.craig-wood.com/nick