File: IO.pm

package info (click to toggle)
libdemeter-perl 0.9.27%2Bds6-9
  • links: PTS, VCS
  • area: contrib
  • in suites: forky, sid, trixie
  • size: 74,028 kB
  • sloc: perl: 73,233; python: 2,196; makefile: 1,999; ansic: 1,368; lisp: 454; sh: 74
file content (598 lines) | stat: -rw-r--r-- 19,482 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
package Demeter::Data::IO;

=for Copyright
 .
 Copyright (c) 2006-2019 Bruce Ravel (http://bruceravel.github.io/home).
 All rights reserved.
 .
 This file is free software; you can redistribute it and/or
 modify it under the same terms as Perl itself. See The Perl
 Artistic License.
 .
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

=cut

use Moose::Role;

use Carp;
use Const::Fast;
use List::MoreUtils qw(none);
use Regexp::Assemble;

use Demeter::Constants qw($NUMBER);

sub save {
  my ($self, $what, $filename, $how) = @_;
  croak("No filename specified for save") unless $filename;
  ($what = 'chi') if (lc($what) eq 'k');
  ($what = 'xmu') if (lc($what) eq 'e');
  croak("Valid save types are: xmu norm chi r q fit bkgsub")
    if ($what !~ m{\A(?:xmu|norm|chi|r|q|fit|bkgsub)\z});
  my $string = q{};
 WHAT: {
    (lc($what) eq 'fit') and do {
      $string = $self->_save_fit_command($filename, $how);
      last WHAT;
    };
    (lc($what) eq 'xmu') and do {
      $self->_update("fft");
      carp("cannot save mu(E) file from chi(k) data\n\n"), return if ($self->datatype eq "chi");
      $string = $self->_save_xmu_command($filename);
      last WHAT;
    };
    (lc($what) eq 'norm') and do {
      $self->_update("fft");
      carp("cannot save norm(E) file from chi(k) data\n\n"), return if ($self->datatype eq "chi");
      $string = $self->_save_norm_command($filename);
      last WHAT;
    };
    (lc($what) eq 'chi') and do {
      $self->_update("fft");
      $string = $self->_save_chi_command('k', $filename);
      last WHAT;
    };
    (lc($what) eq 'r') and do {
      $self->_update("bft");
      $self->dispense('process', 'dphase');
      $string = $self->_save_chi_command('r', $filename);
      last WHAT;
    };
    (lc($what) eq 'q') and do {
      $self->_update("all");
      $string = $self->_save_chi_command('q', $filename);
      last WHAT;
    };
    (lc($what) eq 'bkgsub') and do {
      $self->_update("all");
      $string = $self->_save_bkgsub_command($filename);
      last WHAT;
    };
  };
  $self->dispose($string);
  return $self;
};


sub _save_chi_command {
  my ($self, $space, $filename) = @_;
  my $pf = $self->po;
  if (not $self->plottable) {
    my $class = ref $self;
    croak("$class objects do not have data that can be saved");
  };
  my $string = q{};
  $space = lc($space);
  croak("Demeter: '$space' is not a valid space for saving chi xdata (k k1 k2 k3 r q)")
    if ($space !~ /\A(?:k$NUMBER?|r|q)\z/); # }

  #my $data = $self->data;
  my $how = ($space eq 'k') ? "chi(k)" :
            ($space eq 'r') ? "chi(R)" :
	                      "chi(q)" ;
  $self->title_glob("dem_data_", $space);

  my ($label, $columns) = (q{}, q{});
  if ($space =~ m{\Ak0?\z}) {
    $self->_update("bft");
    if ($self->co->default('file', 'chik_out') eq 'all') {
      $string = $self->template("process", "save_chik",  {filename => $filename,
							  titles   => "dem_data_*"});
    } else {
      $string = $self->template("process", "save_chikw", {filename => $filename,
							  titles   => "dem_data_*"});
    };
  } elsif ($space =~ /\Ak($NUMBER)/) {
    carp("Use file->chik_out configuration parameter for arbitrary wight chi(k) files");
  } elsif ($space eq 'r') {
    $self->_update("all");
    $string  = $self->template('process', 'dphase');
    $string .= $self->template("process", "save_chir", {filename => $filename,
						       titles   => "dem_data_*"});
  } elsif ($space eq 'q') {
    $self->_update("all");
    $string = $self->template("process", "save_chiq", {filename => $filename,
						       titles	  => "dem_data_*",});
  } else {
    croak("Demeter::save: How did you get here?");
  }

  return $string;
};



## need to include the data's titles in write_data() command
sub _save_fit_command {
  my ($self, $filename, $how) = @_;
  $how ||= q{};
  croak("No filename specified for save_fit") unless $filename;
  ($how = "k1")   if ($how =~ m{chi(?:|k1?)});
  ($how = "k2")   if ($how eq 'chik2');
  ($how = "k3")   if ($how eq 'chik3');
  ($how = "rmag") if ($how eq 'chir_mag');
  ($how = "rre")  if ($how eq 'chir_re');
  ($how = "rim")  if ($how eq 'chir_im');
  ($how = "qmag") if ($how eq 'chiq_mag');
  ($how = "qre")  if ($how eq 'chiq_re');
  ($how = "qim")  if ($how eq 'chiq_im');

  my $template = ($how eq 'k1')   ? 'save_fit_kw'
               : ($how eq 'k2')   ? 'save_fit_kw'
               : ($how eq 'k3')   ? 'save_fit_kw'
               : ($how eq 'rmag') ? 'save_fit_r'
               : ($how eq 'rre')  ? 'save_fit_r'
               : ($how eq 'rim')  ? 'save_fit_r'
               : ($how eq 'qmag') ? 'save_fit_q'
               : ($how eq 'qre')  ? 'save_fit_q'
               : ($how eq 'qim')  ? 'save_fit_q'
               :                    'save_fit';
  my $suffix = ($how eq 'rmag') ? 'chir_mag'
             : ($how eq 'rre')  ? 'chir_re'
             : ($how eq 'rim')  ? 'chir_im'
	     : ($how eq 'qmag') ? 'chiq_mag'
             : ($how eq 'qre')  ? 'chiq_re'
             : ($how eq 'qim')  ? 'chiq_im'
	     :                    q{};
  my $kweight = ($how eq 'k1')      ? 1
              : ($how eq 'k2')      ? 2
              : ($how eq 'k3')      ? 3
              : ($how eq 'k')       ? 0
	      : ($how =~ m{\A[rq]}) ? $self->data->get_kweight
	      :                       undef;

  if ($how =~ m{\A[rq]}) {
    $self->_update('all');
    $self->part_fft('fit');
    $self->part_fft('res');
    $self->part_fft('bkg') if $self->fit_do_bkg;
  };
  if ($how =~ m{\Aq}) {
    $self->part_bft('fit');
    $self->part_bft('res');
    $self->part_bft('bkg') if $self->fit_do_bkg;
  };
  $self->title_glob("dem_data_", "f", $how);

  $how ||= 'k';
  $self->running(substr($how, 0, 1), $kweight) if defined($kweight);
  my $command = $self-> template("fit", $template, {filename => $filename,
						    titles   => "dem_data_*",
						    suffix   => $suffix,
						    kweight  => $kweight||0,
						   });
  return $command;
};

sub _save_bkgsub_command {
  my ($self, $filename) = @_;
  croak("No filename specified for save_bkgsub") unless $filename;
  $self->title_glob("dem_data_", "f");
  my $command = $self-> template("fit", "save_bkgsub", {filename => $filename,
							titles   => "dem_data_*"});
  return $self;
};


## xmu norm der nder sec nsec
## chi chik chik2 chik3
## chir_mag chir_re chir_im chir_phas
## chiq_mag chiq_re chiq_im chiq_pha
sub save_many {
  my ($self, $outfile, $which, @groups) = @_;
  my $command = $self->_save_many_command($outfile, $which, @groups);
  #print $/, $command, $/;
  $self->dispose($command);
  return $self;
};
sub _save_many_command {
  my ($self, $outfile, $which, @groups) = @_;
  ($which = "chik1") if ($which eq 'chik');
  ($which = "chik1") if ($which eq 'k1');
  ($which = "chik2") if ($which eq 'k2');
  ($which = "chik3") if ($which eq 'k3');
  ($which = "chir_mag") if ($which eq 'rmag');
  ($which = "chir_re")  if ($which eq 'rre');
  ($which = "chir_im")  if ($which eq 'rim');
  ($which = "chiq_mag") if ($which eq 'qmag');
  ($which = "chiq_re")  if ($which eq 'qre');
  ($which = "chiq_im")  if ($which eq 'qim');
  my $e_regexp = Regexp::Assemble->new()->add(qw(xmu norm der nder sec nsec))->re;
  my $n_regexp = Regexp::Assemble->new()->add(qw(norm nder nsec))->re;
  my $k_regexp = Regexp::Assemble->new()->add(qw(chi chik chik2 chik3))->re;
  my ($level, $space) = ($which =~ m{\A$n_regexp\z}) ? ('fft', 'energy')
                      : ($which =~ m{\Achir})        ? ('bft', 'r')
                      : ($which =~ m{\Achiq})        ? ('all', 'q')
                      : ($which =~ m{\Achi})         ? ('fft', 'k')
                      : ($which =~ m{\Adph})         ? ('bft', 'r')
	              :                                ('data', 'energy');
  $self->mo->standard($self);
  my $command = q{};

  unshift @groups, $self if (none {$self->group eq $_->group} @groups);

  if ($which =~ m{\Achik(\d*)\z}) {
    my $w = $1 || 1;
    $self -> co -> set(chik => $w);
  };
  foreach my $g (@groups) {
    next if ((ref($g) =~ m{VPath}) and ($level !~ m{(?:fft|bft|all)}));
    if (ref($g) =~ m{ScatteringPath}) {
      croak "save_many can take Data, Path, and Path-like objects as its argument, but cannot take ScatteringPath objects";
    };
    $g->_update($level);
    $g->dispense('process', 'dphase') if ($which eq 'dph');
    if ($which =~ m{\Achik(\d*)\z})  { # make k-weighted chi(k) array
      $command .= $g->template("process", "chikn");
    } elsif ($which =~ m{$e_regexp}) { # interpolate energy data onto $self's grid
      my $this = $which;
      $this = 'flat' if (($which eq 'norm') and $g->bkg_flatten);
      $command .= ($g->group eq $self->group)
	        ? $g->template("process", "replicate",   {a=>$this, b=>"int"})
	        : $g->template("process", "interpolate", {suffix=>$this});
    };
  };
  $self -> co -> set(many_which  => $which,
		     many_suffix => ($which =~ m{$e_regexp}) ? 'int' : $which,
		     many_space  => $space,
		     many_file   => $outfile,
		     many_list   => \@groups,
		    );
  #{ local $|=1; print '>' . $self->co->get('save_with_multipliers') . '<';}
  if ($space eq 'k') {		# files in k have 2 abscissa columns
    $command .= $self-> template("process", "save_many_header_k");
    $command .= $self-> template("process", "save_many_k");
  } else {
    $command .= $self-> template("process", "save_many_header");
    $command .= $self-> template("process", "save_many");
  };
  if ($which =~ m{\A(?:$e_regexp|chik(?:\d*))\z}) {
    $command .= $self->template("process", "erase_chikn");
  };

  $self->mo->standard(q{});
  return $command;
};


sub data_parameter_report {
  my ($self, $include_rfactor) = @_;
  my $string = $self->data->template("report", "data_report");
  $string =~ s/\+ \-/- /g;
  return $string;
};
sub fit_parameter_report {
  my ($self, $include_rfactor, $fit_performed) = @_;
  $include_rfactor ||= 0;
  #$include_rfactor = 0;
  $fit_performed   ||= 0;
  my $string = q{};
  #if ($include_rfactor and $fit_performed) {	# only print this for a multiple data set fit
  #if ($fit_performed) {	# only print this for a multiple data set fit
    $string = $self->data->template("report", "fit_report_rfact");
  #} else {
  #  $string = $self->data->template("report", "fit_report");
  #};
  return $string;
};

sub rfactor {
  return q{};
};


const my %MU_HASH         => (1=>'energy eV', 2=>'xmu',3=>'bkg',     4=>'pre_edge', 5=>'post_edge', 6=>'der',       7=>'sec', 8=>'i0', 9=>'chi(e)');
const my %NORM_HASH       => (1=>'energy eV',          2=>'norm',    3=>'nbkg',     4=>'flat',      5=>'fbkg',      6=>'nder',    7=>'nsec');
const my %CHIK_HASH       => (1=>'k inverse Angstrom', 2=>'chi',     3=>'chik',     4=>'chik2',     5=>'chik3',     6=>'window',  7=>'energy');
const my %CHIKW_HASH      => (1=>'k inverse Angstrom', 2=>'chi');
const my %CHIR_HASH       => (1=>'R Angstrom',         2=>'chir_re', 3=>'chir_im',  4=>'chir_mag',  5=>'chir_pha',  6=>'window',  7=>'deriv_pha');
const my %CHIQ_HASH       => (1=>'k inverse Angstrom', 2=>'chi_re',  3=>'chi_im',   4=>'chi_mag',   5=>'chi_pha',   6=>'window',  7=>'chi');
my %FIT_HASH = (1=>'k inverse Angstrom', 2=>'chi',     3=>'fit',     4=>'residual', 5=>'running',   6=>'window');

sub title_glob {
  my ($self, $globname, $space, $how) = @_;
  $how ||= q{};
  my $data = $self->data;
  $space = lc($space);
  my $type = ($space eq 'e') ? " mu(E)"   :
             ($space eq 'n') ? " norm(E)" :
             ($space eq 'k') ? " chi(k)"  :
             ($space eq 'r') ? " chi(R)"  :
             ($space eq 'q') ? " chi(q)"  :
             ($space eq 'f') ? " fit"     :
	                       q{}        ;

  my $save_columns = {};
  my $hash = {};
  $save_columns = $data->xdi->metadata->{Column} if ($data->xdi);
  #Demeter->Dump($save_columns);
 COLUMNS: {
    ($space eq 'e') and do {
      $hash = \%MU_HASH;
      last COLUMNS;
    };
    ($space eq 'n') and do {
      $hash = \%NORM_HASH;
      last COLUMNS;
    };
    ($space eq 'k') and do {
      $hash = \%CHIK_HASH;
      last COLUMNS;
    };
    ($space eq 'r') and do {
      $hash = \%CHIR_HASH;
      last COLUMNS;
    };
    ($space eq 'q') and do {
      $hash = \%CHIQ_HASH;
      last COLUMNS;
    };
    ($space eq 'f') and do {	# this got messy!
      $hash = \%FIT_HASH;
      if ($how eq 'rmag') {
	$hash->{1} = $CHIR_HASH{1};
	$hash->{2} = $CHIR_HASH{4};
      } elsif ($how eq 'rre') {
	$hash->{1} = $CHIR_HASH{1};
	$hash->{2} = $CHIR_HASH{2};
      } elsif ($how eq 'rim') {
	$hash->{1} = $CHIR_HASH{1};
	$hash->{2} = $CHIR_HASH{3};
      } elsif ($how eq 'qmag') {
	$hash->{1} = $CHIQ_HASH{1};
	$hash->{2} = $CHIQ_HASH{4};
      } elsif ($how eq 'qre') {
	$hash->{1} = $CHIQ_HASH{1};
	$hash->{2} = $CHIQ_HASH{2};
      } elsif ($how eq 'qim') {
	$hash->{1} = $CHIQ_HASH{1};
	$hash->{2} = $CHIQ_HASH{3};
      };
      if ($self->fit_do_bkg) {
	$hash->{7} = $hash->{6};
	$hash->{6} = 'background';
      };
      last COLUMNS;
    };
  };
  $self->xdi_set_columns($hash) if ($data->xdi);

  $self->po->kweight($1) if ($how =~ m{k(\d)});
  my $which = ($space eq 'f') ? 'fit' : 'data';
  $self->xdi_output_header($which, q{}, $hash);
  $self->xdi_set_columns($save_columns) if ($data->xdi);
  return $self;
};


sub read_fit {
  my ($self, $filename) = @_;
  croak("No filename specified for read_fit") unless $filename;
  my $command = $self-> template("fit", "read_fit", {filename => $filename,});
  ##print $command, $/, $/;
  $self->dispose($command);
  $self->update_fft(1);
  $self->po->plot_fit(1);
  return $self;
};
sub readfromfit {
  my ($self, $filename) = @_;
  croak("No filename specified for read_fit") unless $filename;
  my $command = $self-> template("fit", "readfromfit", {filename => $filename,});
  ##print $command, $/, $/;
  $self->dispose($command);
  $self->update_fft(1);
  $self->po->plot_fit(1);
  return $self;
};
sub just_fit {
  my ($self, $filename) = @_;
  croak("No filename specified for just_fit") unless $filename;
  my $command = $self-> template("fit", "just_fit", {filename => $filename,});
  ##print $command, $/, $/;
  $self->dispose($command);
  $self->set(update_fft=>1, update_data=>0, update_columns=>0, update_norm=>0, update_bkg=>0, is_fit=>1);
  return $self;
};




1;


=head1 NAME

Demeter::Data::IO - Data Input/Output methods for Demeter

=head1 VERSION

This documentation refers to Demeter version 0.9.26.

=head1 SYNOPSIS

  use Demeter;
  my $data  = Demeter::Data -> new(file=>'t/fe.060', @common_attributes);
  $data->save('xmu', 'data.xmu');

=head1 DESCRIPTION

This Demeter::Data role contains methods for dealing
with data input/output.

=head1 METHODS

=over 4

=item C<save>

This method is a wrapper around command generators for saving the
various kinds of output files.  The syntax is

  $dataobject -> save($type, $filename);

The C<$type> argument is one of C<xmu>, C<norm>, C<chi>, C<r>, C<q>,
C<fit>, and C<bkgsub>.  The second argument is the output file name.

This method will automatically generate useful headers for the output
data file.  These headers will include the title lines associated with
the data and the text of the C<fit_parameter_report> method.

=over 4

=item C<xmu>

This is a seven column file of energy, mu(E), bkg(E), pre_edge(E),
post_edge(E), first derivative of mu(E), and second derivative of
mu(E).

=item C<norm>

This is a seven column file of energy, norm(E), normalized bkg(E),
flattened mu(E), flattened bkg(E), first derivative of norm(E), and
second derivative of norm(E).

=item C<chi>

This is a five column file of k, chi(k), k*chi(k), k^2*chi(k),
k^3*chi(k), and the window in k.

=item C<r>

This is a six column file of R, real part of chi(r), imaginary part of
chi(r), magnitude of chi(r), phase of chi(r), and the window in R.
The current value of kweight of the Plot object is used to generate chi(R).

=item C<q>

This is a seven column file of q, real part of chi(q), imaginary part
of chi(q), magnitude of chi(q), phase of chi(q), the window in k, the
k-weighted chi(k) used in the Fourier transform.  The current value of
kweight of the Plot object is used to generate chi(R).

=item C<fit>

This is one of a variety of five or six column files.  The default fit
file contains k, chi(k), the fit in k, the residual in k, the
background in k (if the background was fit), and the window.  When
passing an additional parameter, the fit file can be written out in
another way.

    $dataobject -> save('fit', 'my.fit', $type);

If C<$type> is left off, the default, un-k-weighted fit file is
written.  The other options for C<$type> are:

    k1 k2 k3 rmag rre rim qmag qre qim

The first three export k-weighted data.  The next three are for the
magnitude, real, or imaginary parts of chi(R).  The final three are
for the magnitude, real, or imaginary parts of chi(q).

This will also accept the the k-, R-, and q-space arguments in the
format accepted the C<save_many> method.

=item C<bkgsub>

Background subtracted chi(k) data....

=back

=item C<save_many>

This method writes out a multi-column file containing a specified
array from many Data objects.

  $dataobjects[0] -> save_many($outfile, $which, @dataobjects);

The first argument is a file name for the output file containing the
data columns.  The second argument is one of:

  xmu norm der sec nder nsec
  chi chik chik2 chik3
  chir_mag chir_re chir_im chir_pha
  chiq_mag chiq_re chiq_im chiq_pha

These are followed by the list of data groups to write to the file.
The refering object will be added to the front of the list if it is
not already included in the list.

The arguments used with the C<save> method when saving a fit are also
accepted for k-, R-, and q-space.

=item C<read_fit>

Reimport a fit written out by a previous instance of Demeter....

=item C<title_glob>

This pushes the title generated by the C<data_parameter_report> or
C<fit_parameter_report> methods into the backend which can then be
accessed by a title glob.

   $object -> title_glob($name, $which)

C<$name> is the base of the name of the string scalars in the backend
and C<$which> is one of C<e>, C<n>, C<k>, C<r>, C<q>, or C<f>
depending on whether you wish to generate title lines for mu(E),
normalized mu(E), chi(k), chi(R), chi(q), or a fit.

=back

=head1 DEPENDENCIES

Demeter's dependencies are in the F<Build.PL> file.

L<Moose> is the basis of Demeter.  This module is implemented as a
role and used by the L<Demeter::Data> object.  I feel obloged
to admit that I am using Moose roles in the most trivial fashion here.
This is mostly an organization tool to keep modules small and methods
organized by common functionality.

=head1 BUGS AND LIMITATIONS

Please report problems to the Ifeffit Mailing List
(L<http://cars9.uchicago.edu/mailman/listinfo/ifeffit/>)

Patches are welcome.

=head1 AUTHOR

Bruce Ravel, L<http://bruceravel.github.io/home>

L<http://bruceravel.github.io/demeter/>

=head1 LICENCE AND COPYRIGHT

Copyright (c) 2006-2019 Bruce Ravel (L<http://bruceravel.github.io/home>). All rights reserved.

This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself. See L<perlgpl>.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

=cut