projekt kivitendo

use Config;

use Math::BigInt;

  # We use Perl's knowledge of string representation for

  # rounding. First, convert the floating point number to a string

  # with a high number of places. Then split the string on the decimal

  # sign and use integer calculation for rounding the decimal places

  # part. If an overflow occurs then apply that overflow to the part

  # before the decimal sign as well using integer arithmetic again.

  my $amount_str = sprintf '%.*f', $places + 10, abs($amount);

  return $amount unless $amount_str =~ m{^(\d+)\.(\d+)$};

  my ($pre, $post)      = ($1, $2);

  my $decimals          = '1' . substr($post, 0, $places);

  my $propagation_limit = $Config{i32size} == 4 ? 7 : 18;

  my $add_for_rounding  = substr($post, $places, 1) >= 5 ? 1 : 0;

  if ($places > $propagation_limit) {

    $decimals = Math::BigInt->new($decimals)->badd($add_for_rounding);

    $pre      = Math::BigInt->new($decimals)->badd(1) if substr($decimals, 0, 1) eq '2';

  } else {

    $decimals += $add_for_rounding;

    $pre      += 1 if substr($decimals, 0, 1) eq '2';

  }

  $amount  = ("${pre}." . substr($decimals, 1)) * ($amount <=> 0);

is($::form->round_amount(143.20, 2), '143.2', '143.20 @ 2');

is($::form->round_amount(143.20, 1), '143.2', '143.20 @ 1');

is($::form->round_amount(143.20, 0), '143',   '143.20 @ 0');

for my $sign (-1, 1) {

  for ("00000".."09999") {

    my $str = my $num = (99 * $sign) . $_;

    $num /= 100;                 # shift decimal

    $num /= 5; $num /= 3;        # calc a bit around

    $num *= 5; $num *= 3;        # dumdidum

    $str =~ s/(..)$/.$1/;       # insert dot

    $str =~ s/0+$//;            # remove trailing 0

    $str =~ s/\.$//;            # remove trailing .

    is $::form->round_amount($num, 2), $str, "round($num, 2) == $str";

  }

}

# what about number that might occur scientific notation?  yes we could just

# check round_amount(1e-12, 2) and watch it blow up, but where's the fun? lets

# check a few Cardano triplets. they are defined by:

#

# ∛(a + b√c) + ∛(a - b√c) - 1 = 0

#

# and the following are solutions for a,b,c:

# (2,1,5)

# (5,2,13)

# (8,3,21)

#

# now calc that, and see what our round makes of the remaining number near zero

#

for ([2,1,5], [5,2,13], [8,3,21]) {

  my ($a,$b,$c) = @$_;

  my $result = ($a + $b * sqrt $c)**(1/3) - ($b * sqrt($c) - $a)**(1/3) - 1;

  is $::form->round_amount($result, 2), '0', "$result => 0";

}

# round to any digit we like

my $pi = atan2 0, -1;

is $::form->round_amount($pi, 0),  '3',             "0 digits of π";

is $::form->round_amount($pi, 1),  '3.1',           "1 digit of π";

is $::form->round_amount($pi, 2),  '3.14',          "2 digits of π";

is $::form->round_amount($pi, 3),  '3.142',         "3 digits of π";

is $::form->round_amount($pi, 4),  '3.1416',        "4 digits of π";

is $::form->round_amount($pi, 5),  '3.14159',       "5 digits of π";

is $::form->round_amount($pi, 6),  '3.141593',      "6 digits of π";

is $::form->round_amount($pi, 7),  '3.1415927',     "7 digits of π";

is $::form->round_amount($pi, 8),  '3.14159265',    "8 digits of π";

is $::form->round_amount($pi, 9),  '3.141592654',   "9 digits of π";

is $::form->round_amount($pi, 10), '3.1415926536', "10 digits of π";

# A LOT of places:

is $::form->round_amount(1.2, 200), '1.2', '1.2 @ 200';