#!/usr/bin/perl

use strict;
use warnings;

my @values = (-10, -9, -8, -7, -6, -5, -4,
              -3, -2, -1, -0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, -0
+.2, -0.1,
              0, 0.1, 0.111111, 0.12, 0.13, 0.16, 0.19, 0.2, 0.21, 0.2
+2,
              0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.00001, 1.001, 1.
+1, 1.2,
              1.3, 1.8, 1.9, 2.000001, 2.001, 2.1, 2.11, 2.2, 2.3, 2.4
+,
              3.1, 4, 5, 6, 7, 8, 9, 10,
              1.16873493792849e-06, 1088.99977561893);

my $wval;
my $wexp;
my $wtanh;
my $wfisher;
my $we2;

# http://mathworld.wolfram.com/HyperbolicTangent.html
sub tanh($) {
    my $in = shift;

    my $a = exp($in);
    my $b = exp(-$in);

    return ($a - $b) / ($a + $b);
}

# https://support.office.com/en-us/article/FISHER-function-D656523C-50
+76-4F95-B87B-7741BF236C69
sub fisher($) {
    my $in = shift;
    return 0 if $in == 1;
    my $a = (1 + $in) / (1 - $in);
    return 0 if $a <= 0;
    return 0.5 * log($a);
}

sub e2($) {
    my $in = shift;
    return 0 if $in == 1;
    return 0.5 * exp((1 + $in) / (1 - $in));
}

map {
    $wval = $_;
    $wexp = exp($_);
    $wtanh = &tanh($_);
    $wfisher = &fisher($_);
    $we2 = &e2($_);
    write;
} @values;

format STDOUT_TOP =
value     exponent(e)          tanh              fisher          e2
--------- -------------------- ----------------- --------------- -----
+----------
.

format STDOUT =
@###.#### @######.############ @###.############ @###.########## @###.
+##########
$wval,   $wexp,           $wtanh,                $wfisher,       $we2
.
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