simplex_table.pl

#! /usr/bin/perl
# Implementation of Simplex Algorithm
# © Mark Hutchinson 2004
# Tableau entry creator

use CGI qw/:standard *table *tr *center/;

sub data_error {
    my $arg;
    $arg=$_[0];
    print header,
          start_html("Error: $arg"),
          h1("Error: $arg"),
          p(
          "There is a problem with the data supplied to the script ",
          i("simplex_table.pl"),
          "."),
          p(
          "Please ",
          a({-href=>"../simplex.html"},"return to the form page"),
          " and try again."),
          end_html;
          exit;
}

if(param() eq ""){
    &data_error("No data");
}else{
    ($vars,$objs,$cons)=(param('novars'),param('noobjs'),param('nocons'));
    foreach $a ($vars,$objs,$cons){
        &data_error("Incomplete data") if $a==0;
        &data_error("Data are not all positive integers") unless $a>0;
    }
    print header,
          start_html("Simplex Algorithm"),
          h1('Simplex Algorithm'),
          p(
          "Please enter the initial tableau in the boxes below.  If you are using artificial variables, select which objective function they exist for (i.e. when they will be removed).  The second line should contain all the variable names.  Select 'Maximise' or 'Minimise' on each objective function depending on what you want.  You may enter fractions in the form a/b/c or b/c (and are strongly advised to do so instead of entering decimals).  If you want a subscript (eg. S<sub>1</sub>) to appear in a name, use '\\' to start and '/' to end it (so S<sub>1</sub> would be '<tt>S\\1/</tt>')."),
          p(
          "'Display as improper fractions' means as <sup>7</sup>/<sub>2</sub> rather than as 3<sup>1</sup>/<sub>2</sub>. (If your browser doesn't show the previous fraction as 'three and a half', it cannot handle certain tags which are used in fractions.  Either use decimals or select 'Display +/- sign in mixed fractions' to display it as 3+<sup>1</sup>/<sub>2</sub>.)"),
          start_form(-method=>'get',-action=>'simplex.pl'),
          hidden('novars',$vars),
          hidden('noobjs',$objs),
          hidden('nocons',$cons),
          start_center,
          start_table({-width=>'100%',-cols=>$vars+2,-border=>1,-cellspacing=>0,-cellpadding=>0}),
          '<tr align="center" valign="top" bgcolor="#DDDDDD">',
          td({-align=>'center'},'Remove after:');
    @temp=('Never');
    for ($i=1;$i<$objs;$i++){
        push @temp,$i;
    }
    for ($i=1;$i<=$vars;$i++){
        $default=param('r'.$i);
        $default=$temp[0] if($default eq '');
        print td({-align=>'center'},popup_menu('r'.$i,\@temp,$default));
    }
    print td({-align=>'center'},'&nbsp;'),
          '</tr><tr align="center" valign="top">',
          td({-align=>'center'},'Names:');
    for ($i=1;$i<=$vars;$i++){
          $default=param('n'.$i);
          print td({-align=>'center'},textfield('n'.$i,$default,'3',));
    }
    print td({-align=>'center'},'RHS'),
          '</tr>';
    for ($j=0;$j<$objs;$j++){
          $default=param('m'.$j);
          $default='Maximise' if($default eq '');
          print '<tr align="center" valign="top" bgcolor="#DDDDDD">',
                td({-align=>'center'},popup_menu('m'.$j,['Maximise','Minimise']));
          for ($i=1;$i<=$vars+1;$i++){
              $default=param('d'.$j.'_'.$i);
              print td({-align=>'center'},textfield('d'.$j.'_'.$i,$default,'3'));
          }
          print '</tr>';
    }
    $put="Constraints:";
    for ($j=0;$j<$cons;$j++){
          print '<tr align="center" valign="top">',
                td({-align=>'center'},$put);
                for ($i=1;$i<=$vars+1;$i++){
                    $default=param('d'.($objs+$j).'_'.$i);
                    print td({-align=>'center'},textfield('d'.($objs+$j).'_'.$i,$default,'3'));
                }
          $put='&nbsp;';
    }
    $default=param('fdsip');
    $default='Display as mixed fractions' if($default eq '');
    print end_table,
          end_center,
          start_table({-cols=>2,-border=>0,-cellspacing=>0,-cellpadding=>0}),
          '<tr align="left" valign="top">',
          td({-valign=>'top'},
          radio_group(-name=>'fdisp',-values=>['Display as mixed fractions','Display as improper fractions','Display as decimals'],-default=>$default,-linebreak=>'true'));
    $default=param('showsign');
    $default='' if($default eq '');
    print td({-valign=>'top'},
          checkbox(-name=>'showsign',-label=>'Display +/- sign in mixed fractions')),
          '</tr>',
          end_table,
          br,
          reset,
          submit('Process'),
          end_form,
          hr,
          font({-size=>'-1'},"This implementation of the Simplex algorithm is &copy; Mark Hutchinson 2004."),
          end_html;
          
          
}

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