package Math::BigRat;
# anythig older is untested, and unlikely to work
-use 5.006002;
+use 5.006;
use strict;
use Math::BigFloat;
@ISA = qw(Math::BigFloat);
-$VERSION = '0.18';
+$VERSION = '0.21';
use overload; # inherit overload from Math::BigFloat
$self->{_d} = $MBI->_copy( $f->{_m} );
# calculate the difference between nE and dE
- # XXX TODO: check that exponent() makes a copy to avoid copy()
- my $diff_e = $nf->exponent()->copy()->bsub( $f->exponent);
+ my $diff_e = $nf->exponent()->bsub( $f->exponent);
if ($diff_e->is_negative())
{
# < 0: mul d with it
# return (later set?) configuration data as hash ref
my $class = shift || 'Math::BigRat';
+ if (@_ == 1 && ref($_[0]) ne 'HASH')
+ {
+ my $cfg = $class->SUPER::config();
+ return $cfg->{$_[0]};
+ }
+
my $cfg = $class->SUPER::config(@_);
# now we need only to override the ones that are different from our parent
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
# Both parts must be objects of whatever we are using today.
- # Second check because Calc.pm has ARRAY res as unblessed objects.
- if (ref($x->{_n}) ne $MBI && ref($x->{_n}) ne 'ARRAY')
+ if ( my $c = $MBI->_check($x->{_n}) )
{
- require Carp; Carp::croak ("n is not $MBI but (".ref($x->{_n}).') in bnorm()');
+ require Carp; Carp::croak ("n did not pass the self-check ($c) in bnorm()");
}
- if (ref($x->{_d}) ne $MBI && ref($x->{_d}) ne 'ARRAY')
+ if ( my $c = $MBI->_check($x->{_d}) )
{
- require Carp; Carp::croak ("d is not $MBI but (".ref($x->{_d}).') in bnorm()');
+ require Carp; Carp::croak ("d did not pass the self-check ($c) in bnorm()");
}
# no normalize for NaN, inf etc.
$x->_new_from_float( $x->_as_float()->blog(Math::BigFloat->new("$y"),@r) );
}
+sub bexp
+ {
+ # set up parameters
+ my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$x,$y,$a,$p,$r) = objectify(2,$class,@_);
+ }
+
+ return $x->binf() if $x->{sign} eq '+inf';
+ return $x->bzero() if $x->{sign} eq '-inf';
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($x,@params) = $x->_find_round_parameters($a,$p,$r);
+
+ # also takes care of the "error in _find_round_parameters?" case
+ return $x if $x->{sign} eq 'NaN';
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # P = undef
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it's not enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ return $x->bone(@params) if $x->is_zero();
+
+ # See the comments in Math::BigFloat on how this algorithm works.
+ # Basically we calculate A and B (where B is faculty(N)) so that A/B = e
+
+ my $x_org = $x->copy();
+ if ($scale <= 75)
+ {
+ # set $x directly from a cached string form
+ $x->{_n} = $MBI->_new("90933395208605785401971970164779391644753259799242");
+ $x->{_d} = $MBI->_new("33452526613163807108170062053440751665152000000000");
+ $x->{sign} = '+';
+ }
+ else
+ {
+ # compute A and B so that e = A / B.
+
+ # After some terms we end up with this, so we use it as a starting point:
+ my $A = $MBI->_new("90933395208605785401971970164779391644753259799242");
+ my $F = $MBI->_new(42); my $step = 42;
+
+ # Compute how many steps we need to take to get $A and $B sufficiently big
+ my $steps = Math::BigFloat::_len_to_steps($scale - 4);
+# print STDERR "# Doing $steps steps for ", $scale-4, " digits\n";
+ while ($step++ <= $steps)
+ {
+ # calculate $a * $f + 1
+ $A = $MBI->_mul($A, $F);
+ $A = $MBI->_inc($A);
+ # increment f
+ $F = $MBI->_inc($F);
+ }
+ # compute $B as factorial of $steps (this is faster than doing it manually)
+ my $B = $MBI->_fac($MBI->_new($steps));
+
+# print "A ", $MBI->_str($A), "\nB ", $MBI->_str($B), "\n";
+
+ $x->{_n} = $A;
+ $x->{_d} = $B;
+ $x->{sign} = '+';
+ }
+
+ # $x contains now an estimate of e, with some surplus digits, so we can round
+ if (!$x_org->is_one())
+ {
+ # raise $x to the wanted power and round it in one step:
+ $x->bpow($x_org, @params);
+ }
+ else
+ {
+ # else just round the already computed result
+ delete $x->{_a}; delete $x->{_p};
+ # shortcut to not run through _find_round_parameters again
+ if (defined $params[0])
+ {
+ $x->bround($params[0],$params[2]); # then round accordingly
+ }
+ else
+ {
+ $x->bfround($params[1],$params[2]); # then round accordingly
+ }
+ }
+ if ($fallback)
+ {
+ # clear a/p after round, since user did not request it
+ delete $x->{_a}; delete $x->{_p};
+ }
+
+ $x;
+ }
+
+sub bnok
+ {
+ # set up parameters
+ my ($self,$x,$y,@r) = (ref($_[0]),@_);
+
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$x,$y,@r) = objectify(2,$class,@_);
+ }
+
+ # do it with floats
+ $x->_new_from_float( $x->_as_float()->bnok(Math::BigFloat->new("$y"),@r) );
+ }
+
sub _float_from_part
{
my $x = shift;
{
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
- return Math::BigInt->new($x) if $x->{sign} !~ /^[+-]$/; # NaN, inf etc
+ # NaN, inf etc
+ return Math::BigInt->new($x->{sign}) if $x->{sign} !~ /^[+-]$/;
my $u = Math::BigInt->bzero();
$u->{sign} = $x->{sign};
Works currently only for integers.
-=head2 blog()
-
-Is not yet implemented.
-
=head2 bround()/round()/bfround()
Are not yet implemented.
Please see the documentation in L<Math::BigInt> for further details.
+=head2 bexp()
+
+ $x->bexp($accuracy); # calculate e ** X
+
+Calculates two integers A and B so that A/B is equal to C<e ** $x>, where C<e> is
+Euler's number.
+
+This method was added in v0.20 of Math::BigRat (May 2007).
+
+See also L<blog()>.
+
+=head2 bnok()
+
+ $x->bnok($y); # x over y (binomial coefficient n over k)
+
+Calculates the binomial coefficient n over k, also called the "choose"
+function. The result is equivalent to:
+
+ ( n ) n!
+ | - | = -------
+ ( k ) k!(n-k)!
+
+This method was added in v0.20 of Math::BigRat (May 2007).
+
=head2 config()
use Data::Dumper;
projects / p5sagit/p5-mst-13.2.git / blobdiff