| Subject: | non-integer A and P make bsqrt/broot/bdiv etc. unhappy |
Consider:
# perl -Mbignum -wle 'print 2->bsqrt(11)'
1.4142135624
# perl -Mbignum -wle 'print 2->bsqrt(11.1)'
1.41421356237
# perl -Mbignum -wle 'print 2->bsqrt(11.6)'
4.4721359550
# perl -Mbignum=l,GMP -wle 'print 2->bsqrt(11)'
1.4142135624
# perl -Mbignum=l,GMP -wle 'print 2->bsqrt(11.1)'
1.0000000000
# perl -Mbignum=l,GMP -wle 'print 2->bsqrt(11.6)'
1.0000000000
In short, passing non-integer arguments as A (number of significant
digits in result) makes bsqrt() (and thus also broot()) and probably
others quite unhappy.
This is easily triggered by naïve code like:
my $n = 100;
my $y = Math::BihgFloat->new(2)->bsqrt($n + $n / 1000 + 4);
bdiv() seems only affected in GMP:
# perl -Mbignum -wle 'print scalar 1->bdiv(3,11)'
0.33333333333
# perl -Mbignum -wle 'print scalar 1->bdiv(3,11.1)'
0.333333333333
# perl -Mbignum -wle 'print scalar 1->bdiv(3,11.6)'
0.333333333333
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,11)'
0.33333333333
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,11.1)'
0
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,11.6)'
0
But P is affected as well as A:
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,undef,-11)'
0.33333333333
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,undef,-11.1)'
0.00000000000
# perl -Mbignum=l,GMP -wle 'print scalar 1->bdiv(3,undef,-11.6)'
0.00000000000
It is unclear if there is a global fix, or if this must be fixed for
each math operation on its own.
Tels