diff options
Diffstat (limited to 'dist/Math-BigInt')
| -rw-r--r-- | dist/Math-BigInt/lib/Math/BigInt.pm | 94 | ||||
| -rw-r--r-- | dist/Math-BigInt/t/bare_mbi.t | 2 | ||||
| -rw-r--r-- | dist/Math-BigInt/t/bigintpm.inc | 175 | ||||
| -rw-r--r-- | dist/Math-BigInt/t/bigintpm.t | 2 | ||||
| -rw-r--r-- | dist/Math-BigInt/t/sub_mbi.t | 2 |
5 files changed, 250 insertions, 25 deletions
diff --git a/dist/Math-BigInt/lib/Math/BigInt.pm b/dist/Math-BigInt/lib/Math/BigInt.pm index c3a05a1567..96f4168317 100644 --- a/dist/Math-BigInt/lib/Math/BigInt.pm +++ b/dist/Math-BigInt/lib/Math/BigInt.pm @@ -1865,25 +1865,84 @@ sub bmodpow return $num if $num->modify('bmodpow'); - # check modulus for valid values - return $num->bnan() if ($mod->{sign} ne '+' # NaN, - , -inf, +inf - || $mod->is_zero()); + # When the exponent 'e' is negative, use the following relation, which is + # based on finding the multiplicative inverse 'd' of 'b' modulo 'm': + # + # b^(-e) (mod m) = d^e (mod m) where b*d = 1 (mod m) - # check exponent for valid values - if ($exp->{sign} =~ /\w/) - { - # i.e., if it's NaN, +inf, or -inf... - return $num->bnan(); - } + $num->bmodinv($mod) if ($exp->{sign} eq '-'); - $num->bmodinv ($mod) if ($exp->{sign} eq '-'); + # Check for valid input. All operands must be finite, and the modulus must be + # non-zero. - # check num for valid values (also NaN if there was no inverse but $exp < 0) - return $num->bnan() if $num->{sign} !~ /^[+-]$/; + return $num->bnan() if ($num->{sign} =~ /NaN|inf/ || # NaN, -inf, +inf + $exp->{sign} =~ /NaN|inf/ || # NaN, -inf, +inf + $mod->{sign} =~ /NaN|inf/ || # NaN, -inf, +inf + $mod->is_zero()); - # $mod is positive, sign on $exp is ignored, result also positive - $num->{value} = $CALC->_modpow($num->{value},$exp->{value},$mod->{value}); - $num; + # Compute 'a (mod m)', ignoring the signs on 'a' and 'm'. If the resulting + # value is zero, the output is also zero, regardless of the signs on 'a' and + # 'm'. + + my $value = $CALC->_modpow($num->{value}, $exp->{value}, $mod->{value}); + my $sign = '+'; + + # If the resulting value is non-zero, we have four special cases, depending + # on the signs on 'a' and 'm'. + + unless ($CALC->_is_zero($num->{value})) { + + # There is a negative sign on 'a' (= $num**$exp) only if the number we + # are exponentiating ($num) is negative and the exponent ($exp) is odd. + + if ($num->{sign} eq '-' && $exp->is_odd()) { + + # When both the number 'a' and the modulus 'm' have a negative sign, + # use this relation: + # + # -a (mod -m) = -(a (mod m)) + + if ($mod->{sign} eq '-') { + $sign = '-'; + } + + # When only the number 'a' has a negative sign, use this relation: + # + # -a (mod m) = m - (a (mod m)) + + else { + # Use copy of $mod since _sub() modifies the first argument. + my $mod = $CALC->_copy($mod->{value}); + $value = $CALC->_sub($mod, $num->{value}); + $sign = '+'; + } + + } else { + + # When only the modulus 'm' has a negative sign, use this relation: + # + # a (mod -m) = (a (mod m)) - m + # = -(m - (a (mod m))) + + if ($mod->{sign} eq '-') { + my $mod = $CALC->_copy($mod->{value}); + $value = $CALC->_sub($mod, $num->{value}); + $sign = '-'; + } + + # When neither the number 'a' nor the modulus 'm' have a negative + # sign, directly return the already computed value. + # + # (a (mod m)) + + } + + } + + $num->{value} = $value; + $num->{sign} = $sign; + + return $num; } ############################################################################### @@ -3212,9 +3271,8 @@ Math::BigInt - Arbitrary size integer/float math package $x->bmuladd($y,$z); # $x = $x * $y + $z $x->bmod($y); # modulus (x % y) - $x->bmodpow($exp,$mod); # modular exponentiation (($num**$exp) % $mod) - $x->bmodinv($mod); # the inverse of $x in the given modulus $mod - + $x->bmodpow($y,$mod); # modular exponentiation (($x ** $y) % $mod) + $x->bmodinv($mod); # modular multiplicative inverse $x->bpow($y); # power of arguments (x ** y) $x->blsft($y); # left shift in base 2 $x->brsft($y); # right shift in base 2 diff --git a/dist/Math-BigInt/t/bare_mbi.t b/dist/Math-BigInt/t/bare_mbi.t index 5f4bf5bfcb..a73fd12337 100644 --- a/dist/Math-BigInt/t/bare_mbi.t +++ b/dist/Math-BigInt/t/bare_mbi.t @@ -1,7 +1,7 @@ #!/usr/bin/perl -w use strict; -use Test::More tests => 3285; +use Test::More tests => 3619; BEGIN { unshift @INC, 't'; } diff --git a/dist/Math-BigInt/t/bigintpm.inc b/dist/Math-BigInt/t/bigintpm.inc index 47daa409a0..da127c3ae1 100644 --- a/dist/Math-BigInt/t/bigintpm.inc +++ b/dist/Math-BigInt/t/bigintpm.inc @@ -1710,6 +1710,27 @@ abc:5:NaN 1234567891:13:6 -1234567891:13:7 324958749843759385732954874325984357439658735983745:2348249874968739:1741662881064902 +-2:1:0 +-1:1:0 +0:1:0 +1:1:0 +2:1:0 +3:1:0 +4:1:0 +-2:3:1 +-1:3:2 +0:3:NaN +1:3:1 +2:3:2 +3:3:NaN +4:3:1 +-2:4:NaN +-1:4:3 +0:4:NaN +1:4:1 +2:4:NaN +3:4:3 +4:4:NaN ## bmodinv Error cases / useless use of function inf:5:NaN 5:inf:NaN @@ -1729,15 +1750,161 @@ abc:5:5:NaN # bmodpow Expected results 0:0:2:1 1:0:2:1 -0:0:1:0 0:3:5:0 -8:7:5032:3840 +-2:-2:1:0 +-1:-2:1:0 +0:-2:1:0 +1:-2:1:0 +2:-2:1:0 +3:-2:1:0 +4:-2:1:0 +-2:-1:1:0 +-1:-1:1:0 +0:-1:1:0 +1:-1:1:0 +2:-1:1:0 +3:-1:1:0 +4:-1:1:0 +-2:0:1:0 +-1:0:1:0 +0:0:1:0 +1:0:1:0 +2:0:1:0 +3:0:1:0 +4:0:1:0 +-2:1:1:0 +-1:1:1:0 +0:1:1:0 +1:1:1:0 +2:1:1:0 +3:1:1:0 +4:1:1:0 +-2:2:1:0 +-1:2:1:0 +0:2:1:0 +1:2:1:0 +2:2:1:0 +3:2:1:0 +4:2:1:0 +-2:3:1:0 +-1:3:1:0 +0:3:1:0 +1:3:1:0 +2:3:1:0 +3:3:1:0 +4:3:1:0 +-2:4:1:0 +-1:4:1:0 +0:4:1:0 +1:4:1:0 +2:4:1:0 +3:4:1:0 +4:4:1:0 +-2:-2:3:1 +-1:-2:3:1 +0:-2:3:NaN +1:-2:3:1 +2:-2:3:1 +3:-2:3:NaN +4:-2:3:1 +-2:-1:3:1 +-1:-1:3:2 +0:-1:3:NaN +1:-1:3:1 +2:-1:3:2 +3:-1:3:NaN +4:-1:3:1 +-2:0:3:1 +-1:0:3:1 +0:0:3:1 +1:0:3:1 +2:0:3:1 +3:0:3:1 +4:0:3:1 +-2:1:3:1 +-1:1:3:2 +0:1:3:0 +1:1:3:1 +2:1:3:2 +3:1:3:0 +4:1:3:1 +-2:2:3:1 +-1:2:3:1 +0:2:3:0 +1:2:3:1 +2:2:3:1 +3:2:3:0 +4:2:3:1 +-2:3:3:1 +-1:3:3:2 +0:3:3:0 +1:3:3:1 +2:3:3:2 +3:3:3:0 +4:3:3:1 +-2:4:3:1 +-1:4:3:1 +0:4:3:0 +1:4:3:1 +2:4:3:1 +3:4:3:0 +4:4:3:1 +-2:-2:4:NaN +-1:-2:4:1 +0:-2:4:NaN +1:-2:4:1 +2:-2:4:NaN +3:-2:4:1 +4:-2:4:NaN +-2:-1:4:NaN +-1:-1:4:3 +0:-1:4:NaN +1:-1:4:1 +2:-1:4:NaN +3:-1:4:3 +4:-1:4:NaN +-2:0:4:1 +-1:0:4:1 +0:0:4:1 +1:0:4:1 +2:0:4:1 +3:0:4:1 +4:0:4:1 +-2:1:4:2 +-1:1:4:3 +0:1:4:0 +1:1:4:1 +2:1:4:2 +3:1:4:3 +4:1:4:0 +-2:2:4:0 +-1:2:4:1 +0:2:4:0 +1:2:4:1 +2:2:4:0 +3:2:4:1 +4:2:4:0 +-2:3:4:0 +-1:3:4:3 +0:3:4:0 +1:3:4:1 +2:3:4:0 +3:3:4:3 +4:3:4:0 +-2:4:4:0 +-1:4:4:1 +0:4:4:0 +1:4:4:1 +2:4:4:0 +3:4:4:1 +4:4:4:0 +8:-1:16:NaN 8:-1:5033:4404 +8:7:5032:3840 +8:8:-5:-4 1e50:1:1:0 98436739867439843769485798542749827593285729587325:43698764986460981048259837659386739857456983759328457:6943857329857295827698367:3104744730915914415259518 # bmodpow Error cases -8:8:-5:NaN -8:-1:16:NaN inf:5:13:NaN 5:inf:13:NaN &bmod diff --git a/dist/Math-BigInt/t/bigintpm.t b/dist/Math-BigInt/t/bigintpm.t index 94f0327790..d16844b347 100644 --- a/dist/Math-BigInt/t/bigintpm.t +++ b/dist/Math-BigInt/t/bigintpm.t @@ -1,7 +1,7 @@ #!/usr/bin/perl -w use strict; -use Test::More tests => 3285 + 6; +use Test::More tests => 3619 + 6; use Math::BigInt lib => 'Calc'; diff --git a/dist/Math-BigInt/t/sub_mbi.t b/dist/Math-BigInt/t/sub_mbi.t index 9f10affa87..a999c0982b 100644 --- a/dist/Math-BigInt/t/sub_mbi.t +++ b/dist/Math-BigInt/t/sub_mbi.t @@ -1,7 +1,7 @@ #!/usr/bin/perl -w use strict; -use Test::More tests => 3285 +use Test::More tests => 3619 + 5; # +5 own tests BEGIN { unshift @INC, 't'; } |