Ovid

I'm sure you remember the good ol' days of typing programs straight out of a book hoping to see something which looks like this:

                     *
                 *   *  *
              *  *   *  *   *
          *   *  *   *  *   *  *
          *   *  *   *  *   *  *
          *   *  *   *  *   *  *
       *  *   *  *   *  *   *  *   *
       *  *   *   *  *   *  *  *   *
       *  *   *   *   *  *  *  *   *
   *   *  *   *    *  *   * *  *   *  *
   *   *  *    *   *    * *  * *   *  *
   *   *   *   *     *   *  **  *  *  *
   *   *   *    *      *    * * *  *  *
   *   *   *     *       *    * *  *  *
   *   *   *      *        *      **  *
   *   *    *       *         *       *
   *   *    *        *           *       *
   *   *     *         *            *        *
   *   *     *          *             *         *
   *   *     *          *               *         *
*  *   *     *           *              *          *
   *   *     *          *               *         *
   *   *     *          *             *         *
   *   *     *         *            *        *
   *   *    *        *           *       *
   *   *    *       *         *       *
   *   *   *      *        *      **  *
   *   *   *     *       *    * *  *  *
   *   *   *    *      *    * * *  *  *
   *   *   *   *     *   *  **  *  *  *
   *   *  *    *   *    * *  * *   *  *
   *   *  *   *    *  *   * *  *   *  *
       *  *   *   *   *  *  *  *   *
       *  *   *   *  *   *  *  *   *
       *  *   *  *   *  *   *  *   *
          *   *  *   *  *   *  *
          *   *  *   *  *   *  *
          *   *  *   *  *   *  *
              *  *   *  *   *
                 *   *  *
                     *

Here's that code translated to Perl.

#!/usr/bin/env perl                                                                                                         

use strict;
use warnings;

# http://www.atariarchives.org/basicgames/showpage.php?page=167
use List::Util 'max';

my $r = 30;
my @f = (
    sub { $r * exp( -$_[0]**2 / 100 ) },
    sub { $r * ( cos( $_[0] / 16 ) + 2 ) },
    sub { $r - $r * sin( $_[0] / 18 ) },
    sub { $r * exp( -cos( $_[0] / 16 ) ) - $r },
    sub { $r * sin( $_[0] / 10 ) },
);

my $f = $f[ rand @f ];

for my $x ( 0 .. ( $r * 2 ) / 1.5 ) {
    $x = $x * 1.5 - $r;
    my $l  = 0;
    my $y1 = 5 * int( sqrt( $r**2 - $x * $x ) / 5 );
    my @line;
    for ( 0 .. ( $y1 * 2 ) / 5 ) {
        my $y = -( ( $_ * 5 ) - $y1 );
        my $z = int( 25 + $f->( sqrt( $x * $x + $y * $y ) ) - .7 * $y );
        next if $z <= $l;
        $l = $z;
        push @line => $z;
    }
    my $string = ' ' x max @line;
    substr $string, $_, 1, '*' foreach @line;    # PRINT TAB(Z);"*";
    print "$string\n";
}

Or translate your own!