[Tutor] greater precision?

[John Collins]

Hi Dave,
> Not silly at all.  I didn't realize str(float) would truncate to 12
> digits either.  I found out by experimenting (with 2.7) in the interpreter.
Very gracious of you to say, and generous of you to trouble yourself
to experiment - thank you very much!
> Note that it may differ from version to version.  And that's another
> reason to use format.
Excellent point!
> But please don't just take the format string I supplied as "right."  It
> is if you always want 15 decimal digits to the right of the decimal
> point.  But if you have a number like 50 thousand, then many of those
> digits to the right are invalid.
Indeed! As you saw, some outputs are, and really must be output as 
integers. A  1 with a decimal point followed by 15 0's would make a real 
mess of the face/vertex designation table. So I have to be careful where 
I invoke
output.write("{0:.15f}".format(x))
or similar, ie, that it operates only on the values I'd like output
that way.
Which raises a question. Is the command 'persistent'? In other words,
if I use it early on, but then wish to output integers, has it 'died
after use', do I need to 'kill it after use', or will python just
default back to what it sees next? I know this sounds silly, but to me
the command 'looks' like it's setting a 'hidden pyton variable' to
"15f" which may need to be explicitly revoked, or not,...???
John.