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<HTML>

<HEAD>
  <TITLE>
  EMBOSS: water
  </TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF" text="#000000">

<table align=center border=0 cellspacing=0 cellpadding=0>
<tr><td valign=top>
<A HREF="/" ONMOUSEOVER="self.status='Go to the EMBOSS home page';return true"><img border=0 src="/images/emboss_icon.jpg" alt="" width=150 height=48></a>
</td>
<td align=left valign=middle>
<b><font size="+6">
water
</font></b>
</td></tr>
</table>
<br>&nbsp;
<p>


<H2>
Wiki
</H2>

The master copies of EMBOSS documentation are available
at <a href="http://emboss.open-bio.org/wiki/Appdocs">
http://emboss.open-bio.org/wiki/Appdocs</a>
on the EMBOSS Wiki.

<p>
Please help by correcting and extending the Wiki pages.

<H2>
    Function
</H2>
Smith-Waterman local alignment of sequences

<H2>
    Description
</H2>

<p><b>water</b> uses the Smith-Waterman algorithm (modified for speed enhancments) to calculate the local alignment of a sequence to one or more other sequences.  The gap insertion penalty, gap extension penalty and substitution matrix used to calculate the alignments are specified.  The output is a standard EMBOSS alignment file.</p>



<H3>
    Algorithm
</H3>

<p>The Smith-Waterman algorithm is a member of the class of algorithms that can calculate the best score and local alignment in the order of mn steps, where <tt>n</tt> and <tt>m</tt> are the lengths of the two sequences. These dynamic programming algorithms were first developed for protein sequence comparison by Smith and Waterman, though similar methods were independently devised during the late 1960's and early 1970's for use in the fields of speech processing and computer science.</p>

<p>Dynamic programming methods ensure the optimal local alignment by exploring all possible alignments and choosing the best. It does this by reading in a scoring matrix that contains values for every possible residue or nucleotide match. <b>water</b> finds an alignment with the maximum possible score where the score of an alignment is equal to the sum of the matches taken from the scoring matrix.</p>

<p>An important problem is the treatment of gaps, i.e., spaces inserted to optimise the alignment score. A penalty is subtracted from the score for each gap opened (the 'gap open' penalty) and a penalty is subtracted from the score for the total number of gap spaces multiplied by a cost (the 'gap extension' penalty). Typically, the cost of extending a gap is set to be 5-10 times lower than the cost for opening a gap.</p>

<p>There are two ways to compute a penalty for a gap of n positions :

gap opening penalty + (n - 1) * gap extension penalty
gap penalty + n * gap length penalty
</p>

<p>The two methods are basically equivalent.  The first way is used by EMBOSS and WU-BLAST.  The second way is used by NCBI-BLAST, GCG, Staden and CLUSTAL. Fasta used it for a long time the first way, but Prof. Pearson decided recently to shift to the second.</p>

<p>The Smith-Waterman algorithm contains no negative scores in the path matrix it creates. The algorithm starts the alignment at the highest path matrix score and works backwards until a cell contains zero. See the Reference Smith et al. for details.</p>



<H2>
    Usage
</H2>
Here is a sample session with <b>water</b>
<p>

<p>
<table width="90%"><tr><td bgcolor="#CCFFFF"><pre>

% <b>water tsw:hba_human tsw:hbb_human </b>
Smith-Waterman local alignment of sequences
Gap opening penalty [10.0]: <b></b>
Gap extension penalty [0.5]: <b></b>
Output alignment [hba_human.water]: <b></b>

</pre></td></tr></table><p>
<p>
<a href="#input.1">Go to the input files for this example</a><br><a href="#output.1">Go to the output files for this example</a><p><p>


<H2>
    Command line arguments
</H2>
<table CELLSPACING=0 CELLPADDING=3 BGCOLOR="#f5f5ff" ><tr><td>
<pre>
Smith-Waterman local alignment of sequences
Version: EMBOSS:6.6.0.0

   Standard (Mandatory) qualifiers:
  [-asequence]         sequence   Sequence filename and optional format, or
                                  reference (input USA)
  [-bsequence]         seqall     Sequence(s) filename and optional format, or
                                  reference (input USA)
   -gapopen            float      [10.0 for any sequence] The gap open penalty
                                  is the score taken away when a gap is
                                  created. The best value depends on the
                                  choice of comparison matrix. The default
                                  value assumes you are using the EBLOSUM62
                                  matrix for protein sequences, and the
                                  EDNAFULL matrix for nucleotide sequences.
                                  (Number from 0.000 to 100.000)
   -gapextend          float      [0.5 for any sequence] The gap extension
                                  penalty is added to the standard gap penalty
                                  for each base or residue in the gap. This
                                  is how long gaps are penalized. Usually you
                                  will expect a few long gaps rather than many
                                  short gaps, so the gap extension penalty
                                  should be lower than the gap penalty. An
                                  exception is where one or both sequences are
                                  single reads with possible sequencing
                                  errors in which case you would expect many
                                  single base gaps. You can get this result by
                                  setting the gap open penalty to zero (or
                                  very low) and using the gap extension
                                  penalty to control gap scoring. (Number from
                                  0.000 to 10.000)
  [-outfile]           align      [*.water] Output alignment file name
                                  (default -aformat srspair)

   Additional (Optional) qualifiers:
   -datafile           matrixf    [EBLOSUM62 for protein, EDNAFULL for DNA]
                                  This is the scoring matrix file used when
                                  comparing sequences. By default it is the
                                  file 'EBLOSUM62' (for proteins) or the file
                                  'EDNAFULL' (for nucleic sequences). These
                                  files are found in the 'data' directory of
                                  the EMBOSS installation.

   Advanced (Unprompted) qualifiers:
   -[no]brief          boolean    [Y] Brief identity and similarity

   Associated qualifiers:

   "-asequence" associated qualifiers
   -sbegin1            integer    Start of the sequence to be used
   -send1              integer    End of the sequence to be used
   -sreverse1          boolean    Reverse (if DNA)
   -sask1              boolean    Ask for begin/end/reverse
   -snucleotide1       boolean    Sequence is nucleotide
   -sprotein1          boolean    Sequence is protein
   -slower1            boolean    Make lower case
   -supper1            boolean    Make upper case
   -scircular1         boolean    Sequence is circular
   -squick1            boolean    Read id and sequence only
   -sformat1           string     Input sequence format
   -iquery1            string     Input query fields or ID list
   -ioffset1           integer    Input start position offset
   -sdbname1           string     Database name
   -sid1               string     Entryname
   -ufo1               string     UFO features
   -fformat1           string     Features format
   -fopenfile1         string     Features file name

   "-bsequence" associated qualifiers
   -sbegin2            integer    Start of each sequence to be used
   -send2              integer    End of each sequence to be used
   -sreverse2          boolean    Reverse (if DNA)
   -sask2              boolean    Ask for begin/end/reverse
   -snucleotide2       boolean    Sequence is nucleotide
   -sprotein2          boolean    Sequence is protein
   -slower2            boolean    Make lower case
   -supper2            boolean    Make upper case
   -scircular2         boolean    Sequence is circular
   -squick2            boolean    Read id and sequence only
   -sformat2           string     Input sequence format
   -iquery2            string     Input query fields or ID list
   -ioffset2           integer    Input start position offset
   -sdbname2           string     Database name
   -sid2               string     Entryname
   -ufo2               string     UFO features
   -fformat2           string     Features format
   -fopenfile2         string     Features file name

   "-outfile" associated qualifiers
   -aformat3           string     Alignment format
   -aextension3        string     File name extension
   -adirectory3        string     Output directory
   -aname3             string     Base file name
   -awidth3            integer    Alignment width
   -aaccshow3          boolean    Show accession number in the header
   -adesshow3          boolean    Show description in the header
   -ausashow3          boolean    Show the full USA in the alignment
   -aglobal3           boolean    Show the full sequence in alignment

   General qualifiers:
   -auto               boolean    Turn off prompts
   -stdout             boolean    Write first file to standard output
   -filter             boolean    Read first file from standard input, write
                                  first file to standard output
   -options            boolean    Prompt for standard and additional values
   -debug              boolean    Write debug output to program.dbg
   -verbose            boolean    Report some/full command line options
   -help               boolean    Report command line options and exit. More
                                  information on associated and general
                                  qualifiers can be found with -help -verbose
   -warning            boolean    Report warnings
   -error              boolean    Report errors
   -fatal              boolean    Report fatal errors
   -die                boolean    Report dying program messages
   -version            boolean    Report version number and exit

</pre>
</td></tr></table>
<P>
<table border cellspacing=0 cellpadding=3 bgcolor="#ccccff">
<tr bgcolor="#FFFFCC">
<th align="left">Qualifier</th>
<th align="left">Type</th>
<th align="left">Description</th>
<th align="left">Allowed values</th>
<th align="left">Default</th>
</tr>

<tr bgcolor="#FFFFCC">
<th align="left" colspan=5>Standard (Mandatory) qualifiers</th>
</tr>

<tr bgcolor="#FFFFCC">
<td>[-asequence]<br>(Parameter 1)</td>
<td>sequence</td>
<td>Sequence filename and optional format, or reference (input USA)</td>
<td>Readable sequence</td>
<td><b>Required</b></td>
</tr>

<tr bgcolor="#FFFFCC">
<td>[-bsequence]<br>(Parameter 2)</td>
<td>seqall</td>
<td>Sequence(s) filename and optional format, or reference (input USA)</td>
<td>Readable sequence(s)</td>
<td><b>Required</b></td>
</tr>

<tr bgcolor="#FFFFCC">
<td>-gapopen</td>
<td>float</td>
<td>The gap open penalty is the score taken away when a gap is created. The best value depends on the choice of comparison matrix. The default value assumes you are using the EBLOSUM62 matrix for protein sequences, and the EDNAFULL matrix for nucleotide sequences.</td>
<td>Number from 0.000 to 100.000</td>
<td>10.0 for any sequence</td>
</tr>

<tr bgcolor="#FFFFCC">
<td>-gapextend</td>
<td>float</td>
<td>The gap extension penalty is added to the standard gap penalty for each base or residue in the gap. This is how long gaps are penalized. Usually you will expect a few long gaps rather than many short gaps, so the gap extension penalty should be lower than the gap penalty. An exception is where one or both sequences are single reads with possible sequencing errors in which case you would expect many single base gaps. You can get this result by setting the gap open penalty to zero (or very low) and using the gap extension penalty to control gap scoring.</td>
<td>Number from 0.000 to 10.000</td>
<td>0.5 for any sequence</td>
</tr>

<tr bgcolor="#FFFFCC">
<td>[-outfile]<br>(Parameter 3)</td>
<td>align</td>
<td>Output alignment file name</td>
<td>(default -aformat srspair)</td>
<td><i>&lt;*&gt;</i>.water</td>
</tr>

<tr bgcolor="#FFFFCC">
<th align="left" colspan=5>Additional (Optional) qualifiers</th>
</tr>

<tr bgcolor="#FFFFCC">
<td>-datafile</td>
<td>matrixf</td>
<td>This is the scoring matrix file used when comparing sequences. By default it is the file 'EBLOSUM62' (for proteins) or the file 'EDNAFULL' (for nucleic sequences). These files are found in the 'data' directory of the EMBOSS installation.</td>
<td>Comparison matrix file in EMBOSS data path</td>
<td>EBLOSUM62 for protein<br>EDNAFULL for DNA</td>
</tr>

<tr bgcolor="#FFFFCC">
<th align="left" colspan=5>Advanced (Unprompted) qualifiers</th>
</tr>

<tr bgcolor="#FFFFCC">
<td>-[no]brief</td>
<td>boolean</td>
<td>Brief identity and similarity</td>
<td>Boolean value Yes/No</td>
<td>Yes</td>
</tr>

<tr bgcolor="#FFFFCC">
<th align="left" colspan=5>Associated qualifiers</th>
</tr>

<tr bgcolor="#FFFFCC">
<td align="left" colspan=5>"-asequence" associated sequence qualifiers
</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sbegin1<br>-sbegin_asequence</td>
<td>integer</td>
<td>Start of the sequence to be used</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -send1<br>-send_asequence</td>
<td>integer</td>
<td>End of the sequence to be used</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sreverse1<br>-sreverse_asequence</td>
<td>boolean</td>
<td>Reverse (if DNA)</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sask1<br>-sask_asequence</td>
<td>boolean</td>
<td>Ask for begin/end/reverse</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -snucleotide1<br>-snucleotide_asequence</td>
<td>boolean</td>
<td>Sequence is nucleotide</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sprotein1<br>-sprotein_asequence</td>
<td>boolean</td>
<td>Sequence is protein</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -slower1<br>-slower_asequence</td>
<td>boolean</td>
<td>Make lower case</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -supper1<br>-supper_asequence</td>
<td>boolean</td>
<td>Make upper case</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -scircular1<br>-scircular_asequence</td>
<td>boolean</td>
<td>Sequence is circular</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -squick1<br>-squick_asequence</td>
<td>boolean</td>
<td>Read id and sequence only</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sformat1<br>-sformat_asequence</td>
<td>string</td>
<td>Input sequence format</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -iquery1<br>-iquery_asequence</td>
<td>string</td>
<td>Input query fields or ID list</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -ioffset1<br>-ioffset_asequence</td>
<td>integer</td>
<td>Input start position offset</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sdbname1<br>-sdbname_asequence</td>
<td>string</td>
<td>Database name</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sid1<br>-sid_asequence</td>
<td>string</td>
<td>Entryname</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -ufo1<br>-ufo_asequence</td>
<td>string</td>
<td>UFO features</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -fformat1<br>-fformat_asequence</td>
<td>string</td>
<td>Features format</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -fopenfile1<br>-fopenfile_asequence</td>
<td>string</td>
<td>Features file name</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td align="left" colspan=5>"-bsequence" associated seqall qualifiers
</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sbegin2<br>-sbegin_bsequence</td>
<td>integer</td>
<td>Start of each sequence to be used</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -send2<br>-send_bsequence</td>
<td>integer</td>
<td>End of each sequence to be used</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sreverse2<br>-sreverse_bsequence</td>
<td>boolean</td>
<td>Reverse (if DNA)</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sask2<br>-sask_bsequence</td>
<td>boolean</td>
<td>Ask for begin/end/reverse</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -snucleotide2<br>-snucleotide_bsequence</td>
<td>boolean</td>
<td>Sequence is nucleotide</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sprotein2<br>-sprotein_bsequence</td>
<td>boolean</td>
<td>Sequence is protein</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -slower2<br>-slower_bsequence</td>
<td>boolean</td>
<td>Make lower case</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -supper2<br>-supper_bsequence</td>
<td>boolean</td>
<td>Make upper case</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -scircular2<br>-scircular_bsequence</td>
<td>boolean</td>
<td>Sequence is circular</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -squick2<br>-squick_bsequence</td>
<td>boolean</td>
<td>Read id and sequence only</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sformat2<br>-sformat_bsequence</td>
<td>string</td>
<td>Input sequence format</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -iquery2<br>-iquery_bsequence</td>
<td>string</td>
<td>Input query fields or ID list</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -ioffset2<br>-ioffset_bsequence</td>
<td>integer</td>
<td>Input start position offset</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sdbname2<br>-sdbname_bsequence</td>
<td>string</td>
<td>Database name</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -sid2<br>-sid_bsequence</td>
<td>string</td>
<td>Entryname</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -ufo2<br>-ufo_bsequence</td>
<td>string</td>
<td>UFO features</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -fformat2<br>-fformat_bsequence</td>
<td>string</td>
<td>Features format</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -fopenfile2<br>-fopenfile_bsequence</td>
<td>string</td>
<td>Features file name</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td align="left" colspan=5>"-outfile" associated align qualifiers
</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -aformat3<br>-aformat_outfile</td>
<td>string</td>
<td>Alignment format</td>
<td>Any string</td>
<td>srspair</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -aextension3<br>-aextension_outfile</td>
<td>string</td>
<td>File name extension</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -adirectory3<br>-adirectory_outfile</td>
<td>string</td>
<td>Output directory</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -aname3<br>-aname_outfile</td>
<td>string</td>
<td>Base file name</td>
<td>Any string</td>
<td>&nbsp;</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -awidth3<br>-awidth_outfile</td>
<td>integer</td>
<td>Alignment width</td>
<td>Any integer value</td>
<td>0</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -aaccshow3<br>-aaccshow_outfile</td>
<td>boolean</td>
<td>Show accession number in the header</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -adesshow3<br>-adesshow_outfile</td>
<td>boolean</td>
<td>Show description in the header</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -ausashow3<br>-ausashow_outfile</td>
<td>boolean</td>
<td>Show the full USA in the alignment</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -aglobal3<br>-aglobal_outfile</td>
<td>boolean</td>
<td>Show the full sequence in alignment</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<th align="left" colspan=5>General qualifiers</th>
</tr>

<tr bgcolor="#FFFFCC">
<td> -auto</td>
<td>boolean</td>
<td>Turn off prompts</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -stdout</td>
<td>boolean</td>
<td>Write first file to standard output</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -filter</td>
<td>boolean</td>
<td>Read first file from standard input, write first file to standard output</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -options</td>
<td>boolean</td>
<td>Prompt for standard and additional values</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -debug</td>
<td>boolean</td>
<td>Write debug output to program.dbg</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -verbose</td>
<td>boolean</td>
<td>Report some/full command line options</td>
<td>Boolean value Yes/No</td>
<td>Y</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -help</td>
<td>boolean</td>
<td>Report command line options and exit. More information on associated and general qualifiers can be found with -help -verbose</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -warning</td>
<td>boolean</td>
<td>Report warnings</td>
<td>Boolean value Yes/No</td>
<td>Y</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -error</td>
<td>boolean</td>
<td>Report errors</td>
<td>Boolean value Yes/No</td>
<td>Y</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -fatal</td>
<td>boolean</td>
<td>Report fatal errors</td>
<td>Boolean value Yes/No</td>
<td>Y</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -die</td>
<td>boolean</td>
<td>Report dying program messages</td>
<td>Boolean value Yes/No</td>
<td>Y</td>
</tr>

<tr bgcolor="#FFFFCC">
<td> -version</td>
<td>boolean</td>
<td>Report version number and exit</td>
<td>Boolean value Yes/No</td>
<td>N</td>
</tr>

</table>


<H2>
    Input file format
</H2>


<b>water</b> reads a nucleotide or protein sequence and one or more
sequence to be aligned to it.
<p>
<p>

The input is a standard EMBOSS sequence query (also known as a 'USA').

<p>
Major sequence database sources defined as standard in EMBOSS
installations include srs:embl, srs:uniprot and ensembl

<p>

Data can also be read from sequence output in any supported format
written by an EMBOSS or third-party application.

<p>
The input format can be specified by using the
command-line qualifier <tt>-sformat xxx</tt>, where 'xxx' is replaced
by the name of the required format.  The available format names are:
gff (gff3), gff2, embl (em), genbank (gb, refseq), ddbj, refseqp, pir
(nbrf), swissprot (swiss, sw), dasgff and debug.

<p>

See:
<A href="http://emboss.sf.net/docs/themes/SequenceFormats.html">
http://emboss.sf.net/docs/themes/SequenceFormats.html</A>
for further information on sequence formats.

<p>


<a name="input.1"></a>
<h3>Input files for usage example </h3>

'tsw:hba_human' is a sequence entry in the example protein database 'tsw'
<p>
<p><h3>Database entry: tsw:hba_human</h3>
<table width="90%"><tr><td bgcolor="#FFCCFF">
<pre>
ID   HBA_HUMAN               Reviewed;         142 AA.
AC   P69905; P01922; Q1HDT5; Q3MIF5; Q53F97; Q96KF1; Q9NYR7; Q9UCM0;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 2.
DT   13-JUN-2012, entry version 108.
DE   RecName: Full=Hemoglobin subunit alpha;
DE   AltName: Full=Alpha-globin;
DE   AltName: Full=Hemoglobin alpha chain;
GN   Name=HBA1;
GN   and
GN   Name=HBA2;
OS   Homo sapiens (Human).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini;
OC   Catarrhini; Hominidae; Homo.
OX   NCBI_TaxID=9606;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] (HBA1).
RX   MEDLINE=81088339; PubMed=7448866; DOI=10.1016/0092-8674(80)90347-5;
RA   Michelson A.M., Orkin S.H.;
RT   "The 3' untranslated regions of the duplicated human alpha-globin
RT   genes are unexpectedly divergent.";
RL   Cell 22:371-377(1980).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA] (HBA2).
RX   MEDLINE=80137531; PubMed=6244294;
RA   Wilson J.T., Wilson L.B., Reddy V.B., Cavallesco C., Ghosh P.K.,
RA   Deriel J.K., Forget B.G., Weissman S.M.;
RT   "Nucleotide sequence of the coding portion of human alpha globin
RT   messenger RNA.";
RL   J. Biol. Chem. 255:2807-2815(1980).
RN   [3]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] (HBA2).
RX   MEDLINE=81175088; PubMed=6452630; DOI=10.1073/pnas.77.12.7054;
RA   Liebhaber S.A., Goossens M.J., Kan Y.W.;
RT   "Cloning and complete nucleotide sequence of human 5'-alpha-globin
RT   gene.";
RL   Proc. Natl. Acad. Sci. U.S.A. 77:7054-7058(1980).
RN   [4]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=6946451; DOI=10.1073/pnas.78.8.5041;
RA   Orkin S.H., Goff S.C., Hechtman R.L.;
RT   "Mutation in an intervening sequence splice junction in man.";
RL   Proc. Natl. Acad. Sci. U.S.A. 78:5041-5045(1981).
RN   [5]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND VARIANT LYS-32.
RX   MEDLINE=21303311; PubMed=11410421;
RA   Zhao Y., Xu X.;
RT   "Alpha2(CD31 AGG--&gt;AAG, Arg--&gt;Lys) causing non-deletional alpha-
RT   thalassemia in a Chinese family with HbH disease.";


<font color=red>  [Part of this file has been deleted for brevity]</font>

FT                                /FTId=VAR_002841.
FT   VARIANT     132    132       S -&gt; P (in Questembert; highly unstable;
FT                                causes alpha-thalassemia).
FT                                /FTId=VAR_002843.
FT   VARIANT     134    134       S -&gt; R (in Val de Marne; O(2) affinity
FT                                up).
FT                                /FTId=VAR_002844.
FT   VARIANT     136    136       V -&gt; E (in Pavie).
FT                                /FTId=VAR_002845.
FT   VARIANT     137    137       L -&gt; M (in Chicago).
FT                                /FTId=VAR_002846.
FT   VARIANT     137    137       L -&gt; P (in Bibba; unstable; causes alpha-
FT                                thalassemia).
FT                                /FTId=VAR_002847.
FT   VARIANT     137    137       L -&gt; R (in Toyama).
FT                                /FTId=VAR_035242.
FT   VARIANT     139    139       S -&gt; P (in Attleboro; O(2) affinity up).
FT                                /FTId=VAR_002848.
FT   VARIANT     140    140       K -&gt; E (in Hanamaki; O(2) affinity up).
FT                                /FTId=VAR_002849.
FT   VARIANT     140    140       K -&gt; T (in Tokoname; O(2) affinity up).
FT                                /FTId=VAR_002850.
FT   VARIANT     141    141       Y -&gt; H (in Rouen/Ethiopia; O(2) affinity
FT                                up).
FT                                /FTId=VAR_002851.
FT   VARIANT     142    142       R -&gt; C (in Nunobiki; O(2) affinity up).
FT                                /FTId=VAR_002852.
FT   VARIANT     142    142       R -&gt; H (in Suresnes; O(2) affinity up).
FT                                /FTId=VAR_002854.
FT   VARIANT     142    142       R -&gt; L (in Legnano; O(2) affinity up).
FT                                /FTId=VAR_002853.
FT   VARIANT     142    142       R -&gt; P (in Singapore).
FT                                /FTId=VAR_002855.
FT   CONFLICT     10     10       N -&gt; H (in Ref. 13; BAD97112).
FT   HELIX         5     16
FT   HELIX        17     21
FT   HELIX        22     36
FT   HELIX        38     43
FT   HELIX        54     72
FT   HELIX        74     76
FT   HELIX        77     80
FT   HELIX        82     90
FT   HELIX        97    113
FT   TURN        115    117
FT   HELIX       120    137
FT   TURN        138    140
SQ   SEQUENCE   142 AA;  15258 MW;  15E13666573BBBAE CRC64;
     MVLSPADKTN VKAAWGKVGA HAGEYGAEAL ERMFLSFPTT KTYFPHFDLS HGSAQVKGHG
     KKVADALTNA VAHVDDMPNA LSALSDLHAH KLRVDPVNFK LLSHCLLVTL AAHLPAEFTP
     AVHASLDKFL ASVSTVLTSK YR
//
</pre>
</td></tr></table><p>
<p><h3>Database entry: tsw:hbb_human</h3>
<table width="90%"><tr><td bgcolor="#FFCCFF">
<pre>
ID   HBB_HUMAN               Reviewed;         147 AA.
AC   P68871; A4GX73; B2ZUE0; P02023; Q13852; Q14481; Q14510; Q45KT0;
AC   Q549N7; Q6FI08; Q6R7N2; Q8IZI1; Q9BX96; Q9UCD6; Q9UCP8; Q9UCP9;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 2.
DT   13-JUN-2012, entry version 108.
DE   RecName: Full=Hemoglobin subunit beta;
DE   AltName: Full=Beta-globin;
DE   AltName: Full=Hemoglobin beta chain;
DE   Contains:
DE     RecName: Full=LVV-hemorphin-7;
GN   Name=HBB;
OS   Homo sapiens (Human).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini;
OC   Catarrhini; Hominidae; Homo.
OX   NCBI_TaxID=9606;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   MEDLINE=77126403; PubMed=1019344;
RA   Marotta C., Forget B., Cohen-Solal M., Weissman S.M.;
RT   "Nucleotide sequence analysis of coding and noncoding regions of human
RT   beta-globin mRNA.";
RL   Prog. Nucleic Acid Res. Mol. Biol. 19:165-175(1976).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   MEDLINE=81064667; PubMed=6254664; DOI=10.1016/0092-8674(80)90428-6;
RA   Lawn R.M., Efstratiadis A., O'Connell C., Maniatis T.;
RT   "The nucleotide sequence of the human beta-globin gene.";
RL   Cell 21:647-651(1980).
RN   [3]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND VARIANT LYS-7.
RX   PubMed=16175509; DOI=10.1086/491748;
RA   Wood E.T., Stover D.A., Slatkin M., Nachman M.W., Hammer M.F.;
RT   "The beta-globin recombinational hotspot reduces the effects of strong
RT   selection around HbC, a recently arisen mutation providing resistance
RT   to malaria.";
RL   Am. J. Hum. Genet. 77:637-642(2005).
RN   [4]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RA   Lu L., Hu Z.H., Du C.S., Fu Y.S.;
RT   "DNA sequence of the human beta-globin gene isolated from a healthy
RT   Chinese.";
RL   Submitted (JUN-1997) to the EMBL/GenBank/DDBJ databases.
RN   [5]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND VARIANT ARG-113.
RA   Cabeda J.M., Correia C., Estevinho A., Cardoso C., Amorim M.L.,
RA   Cleto E., Vale L., Coimbra E., Pinho L., Justica B.;
RT   "Unexpected patterns of globin mutations in thalassemia patients from
RT   north of Portugal.";


<font color=red>  [Part of this file has been deleted for brevity]</font>

FT   VARIANT     141    141       A -&gt; V (in Puttelange; polycythemia; O(2)
FT                                affinity up).
FT                                /FTId=VAR_003082.
FT   VARIANT     142    142       L -&gt; R (in Olmsted; unstable).
FT                                /FTId=VAR_003083.
FT   VARIANT     143    143       A -&gt; D (in Ohio; O(2) affinity up).
FT                                /FTId=VAR_003084.
FT   VARIANT     144    144       H -&gt; D (in Rancho Mirage).
FT                                /FTId=VAR_003085.
FT   VARIANT     144    144       H -&gt; P (in Syracuse; O(2) affinity up).
FT                                /FTId=VAR_003087.
FT   VARIANT     144    144       H -&gt; Q (in Little Rock; O(2) affinity
FT                                up).
FT                                /FTId=VAR_003086.
FT   VARIANT     144    144       H -&gt; R (in Abruzzo; O(2) affinity up).
FT                                /FTId=VAR_003088.
FT   VARIANT     145    145       K -&gt; E (in Mito; O(2) affinity up).
FT                                /FTId=VAR_003089.
FT   VARIANT     146    146       Y -&gt; C (in Rainier; O(2) affinity up).
FT                                /FTId=VAR_003090.
FT   VARIANT     146    146       Y -&gt; H (in Bethesda; O(2) affinity up).
FT                                /FTId=VAR_003091.
FT   VARIANT     147    147       H -&gt; D (in Hiroshima; O(2) affinity up).
FT                                /FTId=VAR_003092.
FT   VARIANT     147    147       H -&gt; L (in Cowtown; O(2) affinity up).
FT                                /FTId=VAR_003093.
FT   VARIANT     147    147       H -&gt; P (in York; O(2) affinity up).
FT                                /FTId=VAR_003094.
FT   VARIANT     147    147       H -&gt; Q (in Kodaira; O(2) affinity up).
FT                                /FTId=VAR_003095.
FT   CONFLICT     26     26       Missing (in Ref. 15; ACD39349).
FT   CONFLICT     42     42       F -&gt; L (in Ref. 13; AAR96398).
FT   HELIX         6     16
FT   TURN         21     23
FT   HELIX        24     35
FT   HELIX        37     42
FT   HELIX        44     46
FT   HELIX        52     57
FT   HELIX        59     77
FT   TURN         78     80
FT   HELIX        82     94
FT   TURN         95     97
FT   HELIX       102    119
FT   HELIX       120    122
FT   HELIX       125    142
FT   HELIX       144    146
SQ   SEQUENCE   147 AA;  15998 MW;  A31F6D621C6556A1 CRC64;
     MVHLTPEEKS AVTALWGKVN VDEVGGEALG RLLVVYPWTQ RFFESFGDLS TPDAVMGNPK
     VKAHGKKVLG AFSDGLAHLD NLKGTFATLS ELHCDKLHVD PENFRLLGNV LVCVLAHHFG
     KEFTPPVQAA YQKVVAGVAN ALAHKYH
//
</pre>
</td></tr></table><p>

<H2>
    Output file format
</H2>

<p>

The output is a standard EMBOSS alignment file. 

<p>

The results can be output in one of several styles by using the
command-line qualifier <tt>-aformat xxx</tt>, where 'xxx' is replaced by
the name of the required format.  Some of the alignment formats can cope
with an unlimited number of sequences, while others are only for pairs
of sequences.  

<p>

The available multiple alignment format names are: multiple, simple,
fasta, msf, clustal, mega, meganon, nexus,, nexusnon, phylip,
phylipnon, selex, treecon, tcoffee, debug, srs.

<p>

The available pairwise alignment format names are: pair, markx0, markx1,
markx2, markx3, markx10, match, sam, bam, score, srspair

<p>

See:
<A href="http://emboss.sf.net/docs/themes/AlignFormats.html">
http://emboss.sf.net/docs/themes/AlignFormats.html</A>
for further information on alignment formats.

<p>

<p>
By default the output is in 'srspair' format.
<p>


<a name="output.1"></a>
<h3>Output files for usage example </h3>
<p><h3>File: hba_human.water</h3>
<table width="90%"><tr><td bgcolor="#CCFFCC">
<pre>
########################################
# Program: water
# Rundate: Mon 15 Jul 2013 12:00:00
# Commandline: water
#    [-asequence] tsw:hba_human
#    [-bsequence] tsw:hbb_human
# Align_format: srspair
# Report_file: hba_human.water
########################################

#=======================================
#
# Aligned_sequences: 2
# 1: HBA_HUMAN
# 2: HBB_HUMAN
# Matrix: EBLOSUM62
# Gap_penalty: 10.0
# Extend_penalty: 0.5
#
# Length: 145
# Identity:      63/145 (43.4%)
# Similarity:    88/145 (60.7%)
# Gaps:           8/145 ( 5.5%)
# Score: 293.5
# 
#
#=======================================

HBA_HUMAN          3 LSPADKTNVKAAWGKVGAHAGEYGAEALERMFLSFPTTKTYFPHF-DLS-     50
                     |:|.:|:.|.|.||||  :..|.|.|||.|:.:.:|.|:.:|..| ||| 
HBB_HUMAN          4 LTPEEKSAVTALWGKV--NVDEVGGEALGRLLVVYPWTQRFFESFGDLST     51

HBA_HUMAN         51 ----HGSAQVKGHGKKVADALTNAVAHVDDMPNALSALSDLHAHKLRVDP     96
                         .|:.:||.|||||..|.::.:||:|::....:.||:||..||.|||
HBB_HUMAN         52 PDAVMGNPKVKAHGKKVLGAFSDGLAHLDNLKGTFATLSELHCDKLHVDP    101

HBA_HUMAN         97 VNFKLLSHCLLVTLAAHLPAEFTPAVHASLDKFLASVSTVLTSKY    141
                     .||:||.:.|:..||.|...||||.|.|:..|.:|.|:..|..||
HBB_HUMAN        102 ENFRLLGNVLVCVLAHHFGKEFTPPVQAAYQKVVAGVANALAHKY    146


#---------------------------------------
#---------------------------------------
</pre>
</td></tr></table><p>

<p>

The <b>Identity:</b> is the percentage of identical matches between the two
sequences over the reported aligned region (including any gaps in the length).

<p>

The <b>Similarity:</b> is the percentage of matches between the two
sequences over the reported aligned region (including any gaps in the length).


<H2>
    Data files
</H2>


For protein sequences EBLOSUM62 is used for the substitution
matrix. For nucleotide sequence, EDNAFULL is used. Others can be specified.

<p>
<p>
EMBOSS data files are distributed with the application and stored
in the standard EMBOSS data directory, which is defined
by the EMBOSS environment variable EMBOSS_DATA.

<p>

To see the available EMBOSS data files, run:
<p>
<pre>
% embossdata -showall
</pre>
<p>
To fetch one of the data files (for example 'Exxx.dat') into your
current directory for you to inspect or modify, run:

<pre>

% embossdata -fetch -file Exxx.dat

</pre>
<p>

Users can provide their own data files in their own directories.
Project specific files can be put in the current directory, or for
tidier directory listings in a subdirectory called
".embossdata". Files for all EMBOSS runs can be put in the user's home
directory, or again in a subdirectory called ".embossdata".

<p>
The directories are searched in the following order:

<ul>
   <li> . (your current directory)
   <li> .embossdata (under your current directory)
   <li> ~/ (your home directory)
   <li> ~/.embossdata
</ul>
<p>

<H2>
    Notes
</H2>

<p>A local alignment searches for regions of local similarity between two sequences and need not include the entire length of the sequences. Local alignment methods are very useful for scanning databases or other circumsatnces when you wish to find matches between small regions of sequences, for example between protein domains.</p>

<H2>
    References
</H2>

<OL>

<LI>Smith TF, Waterman MS (1981) J. Mol. Biol 147(1);195-7

</OL>


<H2>
    Warnings
</H2>

<p>Local alignment methods only report the best matching areas between two sequences - there may be a large number of alternative local alignments that do not score as highly. If two proteins share more than one common region, for example one has a single copy of a particular domain while the other has two copies, it may be possible to "miss" the second and subsequent alignments. You will be able to see this situation if you have done a dotplot and your local alignment does not show all the features you expected to see.</p>

<p><b>water</b> is for aligning the best matching subsequences of two sequences. It does not necessarily align whole sequences against each other; you should use <b>needle</b> if you wish to align closely related sequences along their whole lengths.</p>

<p>A true Smith Waterman implementation like <b>water</b> needs memory proportional to the product of the sequence lengths. For two sequences of length 10,000,000 and 1,000 it therefore needs memory proportional to 10,000,000,000 characters. Two arrays of this size are produced, one of ints and one of floats so multiply that figure by 8 to get the memory usage in bytes. That doesn't include other overheads. Therefore only use <b>water</b> and <b>needle</b> for accurate alignment of reasonably short sequences. It should not be used with very large sequences unless you have a lot of memory and a lot of time. If you run out of memory, try using <b>supermatcher</b> or <b>matcher</b> instead.</p>




<H2>
    Diagnostic Error Messages
</H2>

<PRE>
Uncaught exception
 Assertion failed
 raised at ajmem.c:xxx
</PRE>
<P>

Probably means you have run out of memory.  Try using
<b>supermatcher</b> or <b>matcher</b> if this happens. 

<H2>
    Exit status
</H2>

    0 if successful.

<H2>
    Known bugs
</H2>

None.


<h2><a name="See also">See also</a></h2>
<table border cellpadding=4 bgcolor="#FFFFF0">
<tr><th>Program name</th>
<th>Description</th></tr>
<tr>
<td><a href="matcher.html">matcher</a></td>
<td>Waterman-Eggert local alignment of two sequences</td>
</tr>

<tr>
<td><a href="seqmatchall.html">seqmatchall</a></td>
<td>All-against-all word comparison of a sequence set</td>
</tr>

<tr>
<td><a href="supermatcher.html">supermatcher</a></td>
<td>Calculate approximate local pair-wise alignments of larger sequences</td>
</tr>

<tr>
<td><a href="wordfinder.html">wordfinder</a></td>
<td>Match large sequences against one or more other sequences</td>
</tr>

<tr>
<td><a href="wordmatch.html">wordmatch</a></td>
<td>Find regions of identity (exact matches) of two sequences</td>
</tr>

</table>
<p>

<b>matcher</b> is a local alignment program that gives as good an
alignment as <b>water</b> but it uses far less memory.  However,
<b>water</b> runs twice as fast as <b>matcher</b>. 

<p>

<b>supermatcher</b> is designed for local alignments of very large
sequences.  It gives good results as long as there is not a significant
amount of insertion or deletion in the alignment. 

<H2>
    Author(s)
</H2>


Alan Bleasby 
<br>
European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK

<p>
Please report all bugs to the EMBOSS bug team (emboss-bug&nbsp;&copy;&nbsp;emboss.open-bio.org) not to the original author.


<H2>
    History
</H2>

Completed 7th July 1999.
<p>
Modified 27th July 1999 - tweaking scoring.
<p>
Modified 22 Oct 2000 - added ID and Similarity scores.

<H2>
    Target users
</H2>
This program is intended to be used by everyone and everything, from naive users to embedded scripts.


<H2>
    Comments
</H2>
None

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