comment on

I don't care what I'm initializing something with, there shouldn't be any way to create $ev such that both $ev and 1-$ev print as "1".

And as for initializing everything as strings, look at this code:

#!perl
use Math::BigFloat;
print ((new Math::BigFloat("1")) -
       exp(new Math::BigFloat("-7") /
             (new Math::BigFloat("10")**(new Math::BigFloat("17")))));
# Properly prints "0"
# (well, something like 7e-17 would be closer, but I'll accept 0)
[download]

Compare it to this code, which is the same but with a use bignum:

#!perl
use bignum;
use Math::BigFloat;
print ((new Math::BigFloat("1")) -
       exp(new Math::BigFloat("-7") /
             (new Math::BigFloat("10")**(new Math::BigFloat("17")))));
# Incorrectly prints "1"
[download]

It would appear then that we have a bug not so much in Math::BigFloat directly, but somewhere in the intersection of Math::BigFloat, bignum, and the magic bignum sprinkles on exp.

@/=map{[/./g]}qw/.h_nJ Xapou cets krht ele_ r_ra/;
map{y/X_/\n /;print}map{pop@$_}@/for@/
[download]

In reply to Re^2: Help me make a test case for Math::BigFloat by fizbin
in thread Help me make a test case for Math::BigFloat by fizbin

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