water



Wiki

   The master copies of EMBOSS documentation are available at
   http://emboss.open-bio.org/wiki/Appdocs on the EMBOSS Wiki.

   Please help by correcting and extending the Wiki pages.

Function

   Smith-Waterman local alignment of sequences

Description

   water 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.

  Algorithm

   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 n and m 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.

   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. water 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.

   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.

   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

   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.

   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.

Usage

   Here is a sample session with water


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


   Go to the input files for this example
   Go to the output files for this example

Command line arguments

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


Input file format

   water reads a nucleotide or protein sequence and one or more sequence
   to be aligned to it.

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

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

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

   The input format can be specified by using the command-line qualifier
   -sformat xxx, 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.

   See: http://emboss.sf.net/docs/themes/SequenceFormats.html for further
   information on sequence formats.

  Input files for usage example

   'tsw:hba_human' is a sequence entry in the example protein database
   'tsw'

  Database entry: tsw:hba_human

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-->AAG, Arg-->Lys) causing non-deletional alpha-
RT   thalassemia in a Chinese family with HbH disease.";


  [Part of this file has been deleted for brevity]

FT                                /FTId=VAR_002841.
FT   VARIANT     132    132       S -> P (in Questembert; highly unstable;
FT                                causes alpha-thalassemia).
FT                                /FTId=VAR_002843.
FT   VARIANT     134    134       S -> R (in Val de Marne; O(2) affinity
FT                                up).
FT                                /FTId=VAR_002844.
FT   VARIANT     136    136       V -> E (in Pavie).
FT                                /FTId=VAR_002845.
FT   VARIANT     137    137       L -> M (in Chicago).
FT                                /FTId=VAR_002846.
FT   VARIANT     137    137       L -> P (in Bibba; unstable; causes alpha-
FT                                thalassemia).
FT                                /FTId=VAR_002847.
FT   VARIANT     137    137       L -> R (in Toyama).
FT                                /FTId=VAR_035242.
FT   VARIANT     139    139       S -> P (in Attleboro; O(2) affinity up).
FT                                /FTId=VAR_002848.
FT   VARIANT     140    140       K -> E (in Hanamaki; O(2) affinity up).
FT                                /FTId=VAR_002849.
FT   VARIANT     140    140       K -> T (in Tokoname; O(2) affinity up).
FT                                /FTId=VAR_002850.
FT   VARIANT     141    141       Y -> H (in Rouen/Ethiopia; O(2) affinity
FT                                up).
FT                                /FTId=VAR_002851.
FT   VARIANT     142    142       R -> C (in Nunobiki; O(2) affinity up).
FT                                /FTId=VAR_002852.
FT   VARIANT     142    142       R -> H (in Suresnes; O(2) affinity up).
FT                                /FTId=VAR_002854.
FT   VARIANT     142    142       R -> L (in Legnano; O(2) affinity up).
FT                                /FTId=VAR_002853.
FT   VARIANT     142    142       R -> P (in Singapore).
FT                                /FTId=VAR_002855.
FT   CONFLICT     10     10       N -> 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
//

  Database entry: tsw:hbb_human

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.";


  [Part of this file has been deleted for brevity]

FT   VARIANT     141    141       A -> V (in Puttelange; polycythemia; O(2)
FT                                affinity up).
FT                                /FTId=VAR_003082.
FT   VARIANT     142    142       L -> R (in Olmsted; unstable).
FT                                /FTId=VAR_003083.
FT   VARIANT     143    143       A -> D (in Ohio; O(2) affinity up).
FT                                /FTId=VAR_003084.
FT   VARIANT     144    144       H -> D (in Rancho Mirage).
FT                                /FTId=VAR_003085.
FT   VARIANT     144    144       H -> P (in Syracuse; O(2) affinity up).
FT                                /FTId=VAR_003087.
FT   VARIANT     144    144       H -> Q (in Little Rock; O(2) affinity
FT                                up).
FT                                /FTId=VAR_003086.
FT   VARIANT     144    144       H -> R (in Abruzzo; O(2) affinity up).
FT                                /FTId=VAR_003088.
FT   VARIANT     145    145       K -> E (in Mito; O(2) affinity up).
FT                                /FTId=VAR_003089.
FT   VARIANT     146    146       Y -> C (in Rainier; O(2) affinity up).
FT                                /FTId=VAR_003090.
FT   VARIANT     146    146       Y -> H (in Bethesda; O(2) affinity up).
FT                                /FTId=VAR_003091.
FT   VARIANT     147    147       H -> D (in Hiroshima; O(2) affinity up).
FT                                /FTId=VAR_003092.
FT   VARIANT     147    147       H -> L (in Cowtown; O(2) affinity up).
FT                                /FTId=VAR_003093.
FT   VARIANT     147    147       H -> P (in York; O(2) affinity up).
FT                                /FTId=VAR_003094.
FT   VARIANT     147    147       H -> 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 -> 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
//

Output file format

   The output is a standard EMBOSS alignment file.

   The results can be output in one of several styles by using the
   command-line qualifier -aformat xxx, 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.

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

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

   See: http://emboss.sf.net/docs/themes/AlignFormats.html for further
   information on alignment formats.

   By default the output is in 'srspair' format.

  Output files for usage example

  File: hba_human.water

########################################
# 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


#---------------------------------------
#---------------------------------------

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

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

Data files

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

   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.

   To see the available EMBOSS data files, run:

% embossdata -showall

   To fetch one of the data files (for example 'Exxx.dat') into your
   current directory for you to inspect or modify, run:

% embossdata -fetch -file Exxx.dat


   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".

   The directories are searched in the following order:
     * . (your current directory)
     * .embossdata (under your current directory)
     * ~/ (your home directory)
     * ~/.embossdata

Notes

   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.

References

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

Warnings

   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.

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

   A true Smith Waterman implementation like water 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 water and needle 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 supermatcher or matcher instead.

Diagnostic Error Messages

Uncaught exception
 Assertion failed
 raised at ajmem.c:xxx

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

Exit status

   0 if successful.

Known bugs

   None.

See also

   Program name     Description
   matcher          Waterman-Eggert local alignment of two sequences
   seqmatchall      All-against-all word comparison of a sequence set
   supermatcher     Calculate approximate local pair-wise alignments of larger
                    sequences
   wordfinder       Match large sequences against one or more other sequences
   wordmatch        Find regions of identity (exact matches) of two sequences

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

   supermatcher 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.

Author(s)

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

   Please report all bugs to the EMBOSS bug team
   (emboss-bug (c) emboss.open-bio.org) not to the original author.

History

   Completed 7th July 1999.

   Modified 27th July 1999 - tweaking scoring.

   Modified 22 Oct 2000 - added ID and Similarity scores.

Target users

   This program is intended to be used by everyone and everything, from
   naive users to embedded scripts.

Comments

   None